[clang] [llvm] [Support][vfs] Remove can_write check when replacing file (PR #219540)

[Michael Kruse via cfe-commits]

Meinersbur wrote:

@cachemeifyoucan You mentioned the commit message should be different. It already says "It keeps the check for append mode". Should anything else be changed (I will remove the footnote before landing, footnotes don't work well in commit messages)?

https://github.com/llvm/llvm-project/pull/219540