[clang] [clang][analyzer] Move checker alpha.security.cert.pos.34c into security.PutenvWithAuto (PR #92424)

[Balázs Kéri via cfe-commits]

balazske wrote:

I moved the checker to `alpha.security` now and changed the name, and made the documentations more exact.

https://github.com/llvm/llvm-project/pull/92424