[llvm] update_test_checks: add new --filter-out-after option (PR #129739)

[Henrik G. Olsson via llvm-commits]

hnrklssn wrote:

How does this work for `update_cc_test_checks`? Does the regex match the lines in the source input, or in the LLVM IR output?

https://github.com/llvm/llvm-project/pull/129739