[clang] [analyzer] Drop assertion enforcing that assume args are known constants (PR #151908)

[Balazs Benics via cfe-commits]

steakhal wrote:

> LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-ubuntu-fast` running on `sie-linux-worker` while building `clang` at step 6 "test-build-unified-tree-check-all".
> 
> Full details are available at: https://lab.llvm.org/buildbot/#/builders/144/builds/32123
> Here is the relevant piece of the build log for the reference

Fixed by 6c9f1ce429809e5a91683ed6cef9a435047bebd1.

https://github.com/llvm/llvm-project/pull/151908