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

[Balazs Benics via cfe-commits]

steakhal wrote:

@tru I have this (https://github.com/llvm/llvm-project/commit/0a1eff2ecedcb11acb3e9d4b75ee1e1bebd69a70) simple patch that I want to backport to clang-21, however, it broke the CI build on main, so there was a followup patch (https://github.com/llvm/llvm-project/commit/6c9f1ce429809e5a91683ed6cef9a435047bebd1) that consolidated the bots.
Do you prefer having these commits separate or squashed on the `release/21.x` branch?

FYI: both of these should apply cleanly if applied in the respective order.

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