[clang] Do not discard cleanups while processing immediate invocation

Since an immediate invocation is a full expression itself - it requires
an additional ExprWithCleanups node, but it can participate to a bigger
full expression which actually requires cleanups to be run after.

Thanks @ilya-biryukov for helping reducing the reproducer and confirming
that the analysis is correct.

Fixes https://github.com/llvm/llvm-project/issues/60709

Reviewed By: ilya-biryukov

Differential Revision: https://reviews.llvm.org/D153962