xs: project updates and fixes

[raphdev]

Updating XS project:

• Removing experimental from MSAN.
• Updating auto ccs

Additionally, we update the build to :

• Reduce the number of metering units. This should fix timeouts -- the majority are test cases that run for too long and do not hit the meter limit.
• Re-enable leak_check_at_exit. We have a custom allocator for fuzzing, so we force purging memory in abort paths (to avoid "leaks" that are transient allocations expected to clean up at exit, which is imminent). As a result, we only report leaks that would have been long-lived, survived VM destruction, and therefore true memory leaks.
• Remove sleep functions from the seed corpus. This should fix timeouts caused by the fuzzer calling functions that sleep indefinitely.

[github-actions]

raphdev has previously contributed to projects/xs. The previous PR was #10106

[raphdev]

Not sure why the header check fails...I manually verified that build.sh has the Apache 2.0 string that the linter checks...