Reduce listener delay for CI agents

[evgenyrp]

Another iteration of listener improvements with a focus on reducing the delay to trigger the agent. This will increase the number of runs when the agent analyzes an intermittent failure (capped at 100 per 24 hours).

Specifically:

• do not perform lengthy extra checks if the test was never intermittent based on tests.firefox.dev data.
• do not wait for the parent build to finish
• some other fixes for the issues the agent found during the iterative process of dry runs and analysis of the logs

Stats from the last tested dry run:

Dry run (16.5 h, autoland)

Metric	Value
Window	Sep 2 17:07 → Sep 3 09:37 (16.5 h)
Distinct failing tasks seen	1315
Test-repair would-triggers	23 (~33 / day)
Build-repair would-triggers	4
Fast path fired	36
Fast-path fires that reached trigger	6
Job end → trigger, fast path	0.1 – 0.6 min
Job end → trigger, wait path	10.2 – 17.1 min
History check → trigger gap	1 – 5 s
Ancestor walk stepped over a pending parent	35
Ancestor walk fail-open after 600 s	3
Fast-path triggers the skipped wait would have dropped	0 (all classified 7–9 h later)
Log-parse wait exhausted (60 s)	2
Cross-push dedupe skips	11
Test triggers later classified intermittent	19 / 23 (fast path 5/6, wait path 14/17)
Budget hits (cap 100)	0
Errors / tracebacks	0

Redelpoyed live for testing

related to #6662

[marco-c]

do not perform lengthy extra checks if the test was never intermittent based on tests.firefox.dev data.

How many tests do we have that were never intermittent? Maybe we can have a configurable threshold instead of 0, say start with a very low number like 0.1%.

[evgenyrp]

do not perform lengthy extra checks if the test was never intermittent based on tests.firefox.dev data.

How many tests do we have that were never intermittent? Maybe we can have a configurable threshold instead of 0, say start with a very low number like 0.1%.

We do check the failure rate against the threshold; see https://github.com/mozilla/bugbug/pull/6782/changes#diff-c516aab8c954b9767286eefb7f8c2cb34ace3122326bbad4dd31760a5e28d413R250

Here's what we have in the logs now:

2026-09-03 14:10:21.024
2026-09-03 21:10:21 INFO    app.flakiness: Test devtools/client/inspector/rules/test/browser_rules_inherited-element-backed-pseudo-elements.js failed 5432 of its last 11690 runs (46.467%); it may be an intermittent
2026-09-03 14:04:08.844
2026-09-03 21:04:08 INFO    app.flakiness: Test toolkit/content/tests/chrome/test_findbar.xhtml failed 1166 of its last 13025 runs (8.952%); it may be an intermittent
2026-09-03 14:03:23.632
2026-09-03 21:03:23 INFO    app.flakiness: Test gfx/layers/apz/test/mochitest/test_group_touchevents-6.html failed 148 of its last 17102 runs (0.865%); it may be an intermittent