Selectively inherit yaml vars in stress trigger jobs

Selectively inherit yaml vars in stress trigger jobs

The parent's global RUNNER_SCRIPT_TIMEOUT: 55m was reaching the stress
and tsan:stress child pipelines via inherited yaml variables, where
inherited values outrank the child's job-level variables. That caused
stress jobs with BIND_STRESS_TESTS_RUN_TIME >= 60 to be killed at 55
minutes, regardless of the per-job RUNNER_SCRIPT_TIMEOUT set in the
generated child config.

Use inherit:variables with a positive list on both trigger jobs:
inherit only CI_REGISTRY_IMAGE so the parent's registry override
(needed for image pulls in the child) flows through, while keeping
RUNNER_SCRIPT_TIMEOUT (and other globals) out of the child pipeline's
variable scope. The per-job RUNNER_SCRIPT_TIMEOUT values set by the
generated child config now take effect.

Assisted-by: Claude:claude-opus-4-7
(cherry picked from commit 73915b73d194c371200ea20d129e3412cf2faa6a)