[llvm] [workflows] Add post-commit job that periodically runs the clang static analyzer (PR #94106)

[Tom Stellard via llvm-commits]

tstellar wrote:

@haoNoQ I think RISCVFoldMasks.cpp has a pathological case that uses a lot of memory.

I've made a few changes based on your suggestions.  I split build and analyze into completely separate steps now.  This should allow us to avoid building some unnecessary targets and the script I use to run the analyzer will keep running if one of the jobs fail.

https://github.com/llvm/llvm-project/pull/94106