[clang] [Clang][OpenMP] Fix `if` clause not affecting `teams` construct (PR #207444)

[Jan André Reuter via cfe-commits]

Thyre wrote:

Tagging for review: @loopacino, @ro-i, @zahiraam

I tried to find some people based on the commit history on `CGStmtOpenMP.cpp`.
Feel free to tag additional reviewers, if necessary.
It would be great if you could find some time to look at the changes. Thanks!

https://github.com/llvm/llvm-project/pull/207444