[clang-tools-extra] [clang-tidy] Change AllowCastToVoid default to true in bugprone-unused-return-value (PR #200173)

[Donát Nagy via cfe-commits]

================

----------------
NagyDonat wrote:

@gamesh411 is on vacation right now and I'm not sure if I have push rights on his `llvm` repo, but we will rebase the patch as soon as possible. 

However, I think we can discuss the high-level "Should we change the default of this flag?" question even if the concrete details of the patch are out of date.

https://github.com/llvm/llvm-project/pull/200173