[foozzie] Test the --turbo-force-mid-tier-regalloc flag

This flag will force the usage of the mid-tier register allocator, which
is otherwise only used for huge functions, hence does not get much
fuzzer coverage.

R=machenbach@chromium.org

Bug: v8:12330
Change-Id: I30b602b54adf858a2a3aaf73d8828875c1f6df7a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3234492Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77500}

tools/clusterfuzz/v8_fuzz_flags.json

@@ -29,5 +29,6 @@
   [0.1, "--no-lazy-feedback-allocation --interrupt-budget=100"],
   [0.05, "--budget-for-feedback-vector-allocation=0"],
   [0.1, "--no-wasm-generic-wrapper"],
+  [0.1, "--turbo-force-mid-tier-regalloc"],
   [0.0001, "--simulate-errors"]
 ]

tools/testrunner/testproc/fuzzer.py

@@ -49,6 +49,7 @@ EXTRA_FLAGS = [
   (0.1, '--stress-wasm-code-gc'),
   (0.1, '--turbo-instruction-scheduling'),
   (0.1, '--turbo-stress-instruction-scheduling'),
+  (0.1, '--turbo-force-mid-tier-regalloc'),
 ]
 
 def random_extra_flags(rng):