Add -failfast flag when the mode is fail_fast

[Rajalakshmi-Girish]

Though there is mention of mode fail_fast, at https://github.com/etcd-io/etcd/blob/main/scripts/test_lib.sh#L252, and usages, there is no actual pass of -failfast flag.

Usages locations:
https://github.com/etcd-io/etcd/blob/main/scripts/test.sh#L163
https://github.com/etcd-io/etcd/blob/main/scripts/test.sh#L168

[ptabor]

I think that the role of this flag was to drive the behavior across many packages rather than pass it down to a specific package to not continue executing other tests in the package.

If I understand the tradeoff with this change is mostly about our pre-merge test:

• tests (if failing) will fail faster
• the results will be less complete (as they will contain only a single failed test, rather than all of them in a single package).

As we expect developer to rerun the whole target locally after fixing a test it sounds like a fair tradeoff.

[Rajalakshmi-Girish]

Will this PR need an LGTM comment to merge? @jmhbnz Can you please help me understand what it needs to merge this one.

[Rajalakshmi-Girish]

Will this PR need an LGTM comment to merge? @jmhbnz Can you please help me understand what it needs to merge this one.

or may be should all checks be successful?

[serathius]

Two maintainer approvals are enough.

[serathius]

Let's wait for test to pass.

[Rajalakshmi-Girish]

Let's wait for test to pass.

Will it auto merge if all tests pass and there are two approvals?