[clang] [analyzer][Z3] Restore the original timeout of 15s (PR #118291)

[Kristóf Umann via cfe-commits]

Szelethus wrote:

I also have some just-in-case measurements cooking to confirm that we don't observe any nondeterminism with these values. Previous measurements of mine were made with _all_ configs set to 0. Our downstream release goes off with the patch totally reverted.

https://github.com/llvm/llvm-project/pull/118291