[github, cmake] Remove macOS workflow workarounds that are no longer #243

Job	Run time
Build lldb / Lit Tests (ubuntu-latest)	3h 0m 20s
Test lld / Lit Tests (ubuntu-latest)	1h 3m 28s
Build lldb / Lit Tests (macOS-11)	3h 20m 9s
Test lld / Lit Tests (macOS-11)	2h 8m 22s
Test llvm,clang,libclc / Lit Tests (ubuntu-latest)	2h 43m 25s
Test llvm,clang,libclc / Lit Tests (macOS-11)	5h 5m 57s
	17h 21m 41s

Provide feedback