[Support] Do not remove lock file on failure (llvm#130834)

Clients of `LockFileManager` call `unsafeRemoveLockFile()` whenever
`tryLock()` fails. However looking at the code, there are no scenarios
where this actually does something useful. This PR removes such calls.

(cherry picked from commit f4d599c)

Author: jansvoboda11

clang/lib/Frontend/CompilerInstance.cpp

@@ -1642,8 +1642,6 @@ static bool compileModuleAndReadASTBehindLock(
       // related errors.
       Diags.Report(ModuleNameLoc, diag::remark_module_lock_failure)
           << Module->Name << toString(std::move(Err));
-      // Clear out any potential leftover.
-      Lock.unsafeRemoveLockFile();
       return compileModuleAndReadASTImpl(ImportingInstance, ImportLoc,
                                          ModuleNameLoc, Module, ModuleFileName);
     }