phase1: AnyBranchScheduler: make treeStableTimer configurable

The AnyBranchScheduler will currently wait for 15 minutes before
starting a build.  If new changes are made on the same branch during
this interval, the timer will be restarted.

For staging repository we want faster feedback loop, so we're going to
use much lower value, thus lets make this configurable and handled via
Ansible.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

phase1/config.ini.example

@@ -19,6 +19,7 @@ password = example
 
 [repo]
 url = https://git.openwrt.org/openwrt/openwrt.git
+tree_stable_timer = 900
 
 # branches should be listed by decreasing build priority order, typically oldest branch first (less build intensive)
 # branch section name should match branch "name" option until signall.sh is reworked

phase1/master.cfg

@@ -61,6 +61,7 @@ work_dir = os.path.abspath(ini["general"].get("workdir", "."))
 scripts_dir = os.path.abspath("../scripts")
 
 repo_url = ini["repo"].get("url")
+tree_stable_timer = ini["repo"].getint("tree_stable_timer", 15 * 60)
 
 rsync_defopts = ["-v", "--timeout=120"]
 
@@ -509,7 +510,7 @@ c["schedulers"].append(
     AnyBranchScheduler(
         name="all",
         change_filter=util.ChangeFilter(branch=branchNames),
-        treeStableTimer=15 * 60,
+        treeStableTimer=tree_stable_timer,
         builderNames=builderNames,
     )
 )