Update release prep merge request template

Update self-review template to add torbrowser_legacy vars to rbm.conf,
and remove firefox-android.

.gitlab/merge_request_templates/relprep.md

@@ -10,10 +10,11 @@
   - [ ] `var/torbrowser_build`: should be `build1`, unless bumping a previous release preparation
   - [ ] `var/browser_release_date`: must not be in the future when we start building
   - [ ] `var/torbrowser_incremental_from` (not needed for Android-only releases)
+  - [ ] `var/torbrowser_legacy_version` (For Tor Browser 14.0.x stable releases only)
+  - [ ] `var/torbrowser_legacy_platform_version` (For Tor Browser 14.0.x stable releases only)
 - [ ] Tag updates:
   - [ ] [Firefox](https://gitlab.torproject.org/tpo/applications/tor-browser/-/tags)
   - [ ] Geckoview - should match Firefox
-  - [ ] [Firefox Android](https://gitlab.torproject.org/tpo/applications/firefox-android/-/tags)
   - Tags might be speculative in the release preparation: i.e., they might not exist yet.
 - [ ] Addon updates:
   - [ ] [NoScript](https://addons.mozilla.org/en-US/firefox/addon/noscript/)