[llvm-gsymutil] Remove '--num-threads' in test (llvm#79934)

Number of threads will automatically be set to a good value

Author: kusmour

llvm/test/tools/llvm-gsymutil/X86/elf-empty-dir.yaml

@@ -1,7 +1,7 @@
 ## Test converting DWARF using relative path
 
 # RUN: yaml2obj %s -o %t
-# RUN: llvm-gsymutil --convert %t -o %t.gsym --segment-size=100000 --num-threads=80 --quiet 2>&1 | FileCheck %s --check-prefix=CONVERT
+# RUN: llvm-gsymutil --convert %t -o %t.gsym --segment-size=100000 --quiet 2>&1 | FileCheck %s --check-prefix=CONVERT
 
 # CONVERT: Input file: {{.*\.yaml\.tmp}}
 # CONVERT: Output file (x86_64): {{.*\.yaml\.tmp\.gsym}}