[clang] [analyzer] Avoid creating LazyCompoundVal when possible (PR #116840)

[Balazs Benics via cfe-commits]

steakhal wrote:

Btw expect more patches about fixing LCVs and overall PostInitializer events and bindings.
Basically, how we model the member initializers and copies. Stay tuned for those, but before that this one is a preparation patch, so I'm excited to see your comments.

https://github.com/llvm/llvm-project/pull/116840