Fix preparing rc candidates for providers (apache#36465)

The last auto-upgrade RC implementd in apache#36441 had a bug - it was bumping
rc even for providers that have been already released. This change fixes
it - it skips packages that already have "final" tag present in the
repo. It also explicitely calls "Apply template update" as optional
step - only needed in case we modify templates and want to update
automatically generated documentation with it.

dev/README_RELEASE_PROVIDER_PACKAGES.md

@@ -29,7 +29,7 @@
 - [Prepare Regular Provider packages (RC)](#prepare-regular-provider-packages-rc)
   - [Increasing version number](#increasing-version-number)
   - [Generate release notes](#generate-release-notes)
-  - [Apply template updates](#apply-template-updates)
+  - [(Optional) Apply template updates](#optional-apply-template-updates)
   - [Open PR with suggested version releases](#open-pr-with-suggested-version-releases)
   - [Build provider packages for SVN apache upload](#build-provider-packages-for-svn-apache-upload)
   - [Build and sign the source and convenience packages](#build-and-sign-the-source-and-convenience-packages)
@@ -262,9 +262,10 @@ breeze release-management prepare-provider-documentation --include-removed-provi
  --base-branch provider-cncf-kubernetes/v4-4 cncf.kubernetes
 ```
 
-## Apply template updates
+## (Optional) Apply template updates
 
-(This step can also be executed independently when needed)
+This step should only be executed if we want to change template files for the providers - i.e. change
+security information, commit/index/README content that is automatically generated.
 
 Regenerate the documentation templates by running the command with
 `--reapply-templates` flag to the command above. This refreshes the content of:

dev/breeze/src/airflow_breeze/prepare_providers/provider_packages.py

@@ -172,6 +172,10 @@ def should_skip_the_package(provider_id: str, version_suffix: str) -> tuple[bool
         return False, version_suffix
     # version_suffix starts with "rc"
     current_version = int(version_suffix[2:])
+    release_tag = get_latest_provider_tag(provider_id, "")
+    if tag_exists_for_provider(provider_id, release_tag):
+        get_console().print(f"[warning]The tag {release_tag} exists. Provider is released. Skipping it.[/]")
+        return True, ""
     while True:
         current_tag = get_latest_provider_tag(provider_id, f"rc{current_version}")
         if tag_exists_for_provider(provider_id, current_tag):