chore(java): update release_type choices to stable and preview (googleapis#1331) (googleapis#1553)

* chore(java): update release_type choices to stable and preview (googleapis#1331)

* chore(java): update release_type choices to stable and preview

* chore: update badge names
Source-Link: googleapis/synthtool@d10357a
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-java:latest@sha256:9669c169d0582f13d6b2d319a43a78fc49f296a883aa48519bd0e5c7d34087c4

* format fix

* 🦉 Updates from OwlBot

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

* 🦉 Updates from OwlBot

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>
Co-authored-by: Emily Ball <[email protected]>

Author: gcf-owl-bot[bot]