[clang] Partially revert "Disable a few formatting options for test/"

The changes to "AlignTrailingComments" and "CommentPragmas" did not
result in what I expected (just leave the special comments alone).

Instead now the following:
  void test() {
    int i; // expected-error
           // expected-warning
  }

is formatted into:
  void test() {
    int i; // expected-error
    // expected-warning
  }

which is even worse.

clang/test/.clang-format

@@ -1,5 +1,3 @@
 BasedOnStyle: LLVM
 ColumnLimit: 0
-AlignTrailingComments: false
-CommentPragmas: "(^ ?CHECK|^ ?expected-)"
 AlwaysBreakTemplateDeclarations: No