[fuzzer] Relax the FileCheck string for test fuzzer-custommutator.test#66343

vitalybuka merged 1 commit intollvm:mainllvm/llvm-project:mainfrom

yingcong-wu:yc/fuzzer/flaky-custommutator-testyingcong-wu/llvm-project:yc/fuzzer/flaky-custommutator-testCopy head branch name to clipboard