siso: Merge fuzzer_long_compile and fuzzer_large_compile

"obj/chrome/test/fuzzing/webidl_fuzzing/webidlfuzzer_proto_gen/webidlfuzzer.pb.o" fails for remote OOM. So, it should use large workers.
https://ci.chromium.org/ui/p/chromium/builders/build/linux-chromeos-build-perf-siso/5581/overview

Also in general, using large worker also help reduce the compile speed. So, "fuzzer_long_compile" also should it.

Bug: 380748579
Change-Id: Iea1c347cba01733f719d5662405f517d922be0ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6044070
Auto-Submit: Junji Watanabe <jwata@google.com>
Reviewed-by: Fumitoshi Ukai <ukai@google.com>
Commit-Queue: Fumitoshi Ukai <ukai@google.com>
Cr-Commit-Position: refs/heads/main@{#1387423}