Rollup merge of #154167 - ujjwalvishwakarma2006:move-lto-tests, r=Kivooeo

ui/lto: move and rename two tests from issues/

Move:
- `tests/ui/issues/issue-44056.rs` -> `tests/ui/lto/lto-avx-target-feature.rs`
    - The first test enables both AVX target features and LTO but does not exercise AVX-specific behavior. The test primarily checks that LTO builds successfully with these flags; place it under `ui/lto` for consistency.
- `tests/ui/issues/issue-51947.rs` -> `tests/ui/lto/lto-weak-merge-functions.rs`
    - The second test exercises weak linkage interacting with LTO (merge-functions), so it should belong in `ui/lto`.

I have also added a commented line at the top of each test file indicating the issue it originated from.

Author: JonathanBrouwer