feat: next release from preview-9.x branch is v9.0.0-alpha.0 (#1558)

* feat: next release from preview-9.x branch is v9.0.0-alpha.0

* feat: next release from preview-9.x branch is v9.0.0-alpha.0

* feat: next release from preview-9.x branch is v9.0.0-alpha.0

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* Update owlbot.py

* Update release-please.yml

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: sofisl

.github/release-please.yml

@@ -1,2 +1,6 @@
 handleGHRelease: true
 releaseType: node
+branches:
+  - handleGHRelease: true
+    releaseType: node
+    branch: preview-9.x

owlbot.py

@@ -17,7 +17,7 @@
 import synthtool.languages.node as node
 from synthtool import shell
 
-node.owlbot_main(templates_excludes=['.github/bug-report.md'])
+node.owlbot_main(templates_excludes=['.github/bug-report.md', '.github/release-please.yml'])
 
 # Regenerate Discovery types.
 shell.run(('npm','run','types'))