[spm]: Clean up timers auto generation logic. (#3523)

Config Reload Enhancements PR sonic-net/SONiC#1203 does not completely remove TIMERs from SONiC Package Manager infra. This PR is intended to complete the original changes.

`Systemd` TIMERs infra was replaced by `hostcfgd` service management.
That was done to improve reliability of service management.

#### What I did
* Removed redundant TIMERs infra

#### How I did it
* Updated SPM auto generation logic

#### How to verify it
1. Install application extension
```bash
spm install --from-tarball <app_ext_path>
```
2. Make sure `delayed` flag is set
```bash
docker image inspect <app_ext_image> | jq '.[].Config.Labels["com.azure.sonic.manifest"]' | python -c 'import sys,ast; print(ast.literal_eval(sys.stdin.read()))' | jq .service.delayed
true
```
3. Check no TIMERs were generated

sonic_package_manager/service_creator/creator.py

@@ -31,7 +31,6 @@
 
 
 SERVICE_FILE_TEMPLATE = 'sonic.service.j2'
-TIMER_UNIT_TEMPLATE = 'timer.unit.j2'
 
 SYSTEMD_LOCATION = '/usr/lib/systemd/system'
 ETC_SYSTEMD_LOCATION = '/etc/systemd/system'
@@ -305,7 +304,7 @@ def generate_service_mgmt(self, package: Package):
         log.info(f'generated {script_path}')
 
     def generate_systemd_service(self, package: Package):
-        """ Generates systemd service(s) file and timer(s) (if needed) for package.
+        """ Generates systemd service(s) file for package.
 
         Args:
             package: Package object to generate service for.
@@ -333,23 +332,6 @@ def generate_systemd_service(self, package: Package):
             render_template(template, output_file, template_vars)
             log.info(f'generated {output_file}')
 
-        if package.manifest['service']['delayed']:
-            template_vars = {
-                'source': get_tmpl_path(TIMER_UNIT_TEMPLATE),
-                'manifest': package.manifest.unmarshal(),
-                'multi_instance': False,
-            }
-            output_file = os.path.join(SYSTEMD_LOCATION, f'{name}.timer')
-            template = os.path.join(TEMPLATES_PATH, TIMER_UNIT_TEMPLATE)
-            render_template(template, output_file, template_vars)
-            log.info(f'generated {output_file}')
-
-            if package.manifest['service']['asic-service']:
-                output_file = os.path.join(SYSTEMD_LOCATION, f'{name}@.timer')
-                template_vars['multi_instance'] = True
-                render_template(template, output_file, template_vars)
-                log.info(f'generated {output_file}')
-
     def update_generated_services_conf_file(self, package: Package, remove=False):
         """ Updates generated_services.conf file.
 

sonic_package_manager/service_creator/feature.py

@@ -105,8 +105,7 @@ def update(self,
                old_manifest: Manifest,
                new_manifest: Manifest):
         """ Migrate feature configuration. It can be that non-configurable
-        feature entries have to be updated. e.g: "delayed" for example if
-        the new feature introduces a service timer or name of the service has
+        feature entries have to be updated. e.g: name of the service has
         changed, but user configurable entries are not changed).
 
         Args:

tests/sonic_package_manager/conftest.py

@@ -412,7 +412,6 @@ def sonic_fs(fs):
     fs.create_dir(SERVICE_MGMT_SCRIPT_LOCATION)
     fs.create_file(GENERATED_SERVICES_CONF_FILE)
     fs.create_file(os.path.join(TEMPLATES_PATH, SERVICE_FILE_TEMPLATE))
-    fs.create_file(os.path.join(TEMPLATES_PATH, TIMER_UNIT_TEMPLATE))
     fs.create_file(os.path.join(TEMPLATES_PATH, SERVICE_MGMT_SCRIPT_TEMPLATE))
     fs.create_file(os.path.join(TEMPLATES_PATH, DOCKER_CTL_SCRIPT_TEMPLATE))
     fs.create_file(os.path.join(TEMPLATES_PATH, DEBUG_DUMP_SCRIPT_TEMPLATE))

tests/sonic_package_manager/test_service_creator.py

@@ -137,20 +137,6 @@ def read_file(name):
     assert not sonic_fs.exists(os.path.join(ETC_SYSTEMD_LOCATION, 'test@2.service.d'))
 
 
-def test_service_creator_with_timer_unit(sonic_fs, manifest, service_creator):
-    entry = PackageEntry('test', 'azure/sonic-test')
-    package = Package(entry, Metadata(manifest))
-    service_creator.create(package)
-
-    assert not sonic_fs.exists(os.path.join(SYSTEMD_LOCATION, 'test.timer'))
-
-    manifest['service']['delayed'] = True
-    package = Package(entry, Metadata(manifest))
-    service_creator.create(package)
-
-    assert sonic_fs.exists(os.path.join(SYSTEMD_LOCATION, 'test.timer'))
-
-
 def test_service_creator_with_debug_dump(sonic_fs, manifest, service_creator):
     entry = PackageEntry('test', 'azure/sonic-test')
     package = Package(entry, Metadata(manifest))
@@ -396,27 +382,6 @@ def test_feature_update(mock_sonic_db, manifest):
     ], any_order=True)
 
 
-def test_feature_registration_with_timer(mock_sonic_db, manifest):
-    manifest['service']['delayed'] = True
-    mock_connector = Mock()
-    mock_connector.get_entry = Mock(return_value={})
-    mock_sonic_db.get_connectors = Mock(return_value=[mock_connector])
-    mock_sonic_db.get_initial_db_connector = Mock(return_value=mock_connector)
-    feature_registry = FeatureRegistry(mock_sonic_db)
-    feature_registry.register(manifest)
-    mock_connector.set_entry.assert_called_with('FEATURE', 'test', {
-        'state': 'disabled',
-        'auto_restart': 'enabled',
-        'high_mem_alert': 'disabled',
-        'set_owner': 'local',
-        'has_per_asic_scope': 'False',
-        'has_global_scope': 'True',
-        'delayed': 'True',
-        'check_up_status': 'False',
-        'support_syslog_rate_limit': 'False',
-    })
-
-
 def test_feature_registration_with_non_default_owner(mock_sonic_db, manifest):
     mock_connector = Mock()
     mock_connector.get_entry = Mock(return_value={})