[lldb][debugserver] Revert "Use llvm::all_of (NFC)" for debugserver

Commit [6d9cd919](https://reviews.llvm.org/rG6d9cd9199a6fdeab0412117bcefc28f625510b61) added a dependency on llvm to debugserver.
This breaks the build. Since we don't want to add a dependency on llvm, this
patch reverts the offending commit.

Differential Revision: https://reviews.llvm.org/D131901