[test] preformat test with update_llc_test_checks.py NFC

Summary:
Prior to landing D76961, preprocess via:
    $ llvm/utils/update_llc_test_checks.py \
      llvm/test/CodeGen/X86/callbr-asm-outputs.ll

Reviewers: void, MaskRay

Reviewed By: void, MaskRay

Subscribers: MaskRay, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77356