[Github] Add timeouts to libc tests (#198934)
None of these jobs do not take anywhere close to the six hour timeout
that Github uses by default. Set timeouts that are 2-3x the typical job
runtime so that if there is a test/build step that hangs indefinitely,
the job times out in a reasonable amount of time and does not hold any
resources that could be used elsewhere.
This should not impact any jobs that do not hang, will not change the
result of jobs that do hang, and means we can more effectively deal with
cases like today where tests were hanging, from a resource perspective.
This is also standard in some other workflows like the main premerge
workflow definition.
