libFuzzer fuzzer-leak.test and fuzzer-finalstats.test are unstable

[DavidSpickett]

compiler-rt/test/fuzzer/fuzzer-leak.test has been the cause of a lot of unrelated failures since buildbot started posting statues to PRs.

For example: #97397 (comment)

I know in general this test can be sensitive to the resources available on the machine at the time, but perhaps something can be done to make it deterministic?

[DavidSpickett]

@kcc

(apologies for the blunt approach here just disabling it completely, I'm not very familiar with the internal workings of the fuzzer)

[DavidSpickett]

#97396 (comment)
#97513 (comment)
#97259 (comment)
#97047 (comment)
#94705 (comment)
#96305 (comment)

Some more examples, in case any pattern emerges when looking at the build times/worker names/etc.

[DavidSpickett]

Also temporarily disabled compiler-rt/test/fuzzer/fuzzer-finalstats.test for the same reasons.

[DavidSpickett]

finalstats potentially fixed by #96914