system-probe: Add pkg/process/monitor to tests (#25463)

* system-probe: Add pkg/process/monitor to tests

The process monitor used by USM lives under pkg/process/monitor and has
a test suite; run it as part of the system-probe tests to prevent it
from breaking.

* system-probe: Fix formatting with ruff

* system-probe: Ignore packages without dirs

If the package does not contain any dirs for the current set of tags,
ignore it instead of reporting empty paths which cause crashes later.
This is needed now since pkg/process/monitor is not available for
Windows.

* Use explicit check

Co-authored-by: Guillermo Julián <gjulianm@users.noreply.github.com>

---------

Co-authored-by: Guillermo Julián <gjulianm@users.noreply.github.com>

tasks/system_probe.py

@@ -42,7 +42,12 @@
 
 KITCHEN_DIR = os.getenv('DD_AGENT_TESTING_DIR') or os.path.normpath(os.path.join(os.getcwd(), "test", "kitchen"))
 KITCHEN_ARTIFACT_DIR = os.path.join(KITCHEN_DIR, "site-cookbooks", "dd-system-probe-check", "files", "default", "tests")
-TEST_PACKAGES_LIST = ["./pkg/ebpf/...", "./pkg/network/...", "./pkg/collector/corechecks/ebpf/..."]
+TEST_PACKAGES_LIST = [
+    "./pkg/ebpf/...",
+    "./pkg/network/...",
+    "./pkg/collector/corechecks/ebpf/...",
+    "./pkg/process/monitor/...",
+]
 TEST_PACKAGES = " ".join(TEST_PACKAGES_LIST)
 TEST_TIMEOUTS = {
     "pkg/network/tracer$": "0",
@@ -794,7 +799,7 @@ def go_package_dirs(packages, build_tags):
 
     target_packages = []
     for pkg in packages:
-        target_packages += (
+        dirs = (
             check_output(
                 f"go list -find -f \"{{{{ .Dir }}}}\" -mod=mod -tags \"{','.join(build_tags)}\" {pkg}",
                 shell=True,
@@ -803,6 +808,9 @@ def go_package_dirs(packages, build_tags):
             .strip()
             .split("\n")
         )
+        # Some packages may not be available on all architectures, ignore them
+        # instead of reporting empty path names
+        target_packages += [dir for dir in dirs if len(dir) > 0]
 
     return target_packages