[chore] Try fixing merge freeze CI again (#13876)

#### Description

Alternative to #13875 and half-revert of #13841: use author login to
find the otelbot in PR CI (which historically seems to work), and use
author email to find it in merge queue CI (as of yet untested).

[Example of the new condition not working in PR
CI](#13874)

Author: jade-guiton-dd

.github/workflows/check-merge-freeze.yml

@@ -24,7 +24,7 @@ jobs:
     # This condition is to avoid blocking the PR causing the freeze in the first place.
     if: |
       (!startsWith(github.event.pull_request.title || github.event.merge_group.head_commit.message, '[chore] Prepare release')) ||
-      ((github.event.pull_request.user.email || github.event.merge_group.head_commit.author.email) != '[email protected]')
+      (!(github.event.pull_request.user.login == 'otelbot[bot]' || github.event.merge_group.head_commit.author.email == '[email protected]'))
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0