[UTC] Indent switch cases (#165212)
LLVM prints switch cases indented by 2 additional spaces, as follows:
```LLVM
switch i32 %x, label %default [
i32 0, label %phi
i32 1, label %phi
]
```
Since this only changes the output IR of update_test_checks.py and does
not change the logic of the File Check Pattern, there seems to be no
need to update the existing test cases.
