Setting test.timeout according to TEST_TIMEOUT

[linzhp]

What type of PR is this?
Bug fix

What does this PR do? Why is it needed?
This is another attempt to make test timeout experience close to "go test". It meets the following requirements:

1. gorountine stack at the time of test termination is printed out
2. "bazel test" doesn't add 15s to the configured timeout (Test binaries swallow SIGTERM; printed stack traces misleading #3875)
3. test.xml reports the test cases executed at the time of timeout if test.v is passed
4. Bazel reports the timed out test as TIMEOUT as opposed to FAIL

This implements the approach described in #3875 (comment)

Which issues(s) does this PR fix?

Fixes #3875

Other notes for review
cc @rickystewart

[fmeum]

That's a clean solution to our problems, thanks!

[sluongng]

This change broke one of our tests which runs sh -c kill -TERM $$ to test the termination of the shell.

We have to register our own signal.Notify as a workaround for that test.
buildbuddy-io/buildbuddy#6436

I think this was the original intention of go/tools/bzltestutil/timeout.go?

[linzhp]

@sluongng @fmeum Maybe we should do this instead here?

	c := make(chan os.Signal, 1)
	signal.Notify(c, syscall.SIGTERM)
	go func() {
		<-c
	}()

[fmeum]

With the intent of this being resettable by signal.Reset? I like that.