[llvm] [CI] Make premerge_advisor_explain write comments (PR #166605)

[Baranov Victor via llvm-commits]

vbvictor wrote:

> @boomanaiden154 I'm seeing a build failure in a PR build that looks like it might be related to this change?

+1 Also seen problems.

[On Linux](https://github.com/llvm/llvm-project/actions/runs/19181031691/job/54837627481?pr=167020):
```
    File "/home/gha/actions-runner/_work/llvm-project/llvm-project/.ci/premerge_advisor_explain.py", line 78, in main
      comment = get_comment(
                ^^^^^^^^^^^^
  TypeError: get_comment() missing 2 required positional arguments: 'pr_number' and 'body'
```

[On Windows](https://github.com/llvm/llvm-project/actions/runs/19181031691/job/54837627484?pr=167020) (different error):
```
  Traceback (most recent call last):
    File "C:\_work\llvm-project\llvm-project\.ci\premerge_advisor_explain.py", line 23, in <module>
      def get_comment_id(platform: str, pr: github.PullRequest.PullRequest) -> int | None:
  TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'
```



https://github.com/llvm/llvm-project/pull/166605