chore(cd): update prerelease docker repository (#14121)

Separate the development docker repository from the production repository.

KAG-6137

Author: AndyZhang0707

.github/workflows/release.yml

@@ -31,7 +31,7 @@ on:  # yamllint disable-line rule:truthy
 env:
   # official release repo
   DOCKER_REPOSITORY: kong/kong
-  PRERELEASE_DOCKER_REPOSITORY: kong/kong
+  PRERELEASE_DOCKER_REPOSITORY: kong/kong-dev
   FULL_RELEASE: ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' || github.actor == 'dependabot[bot]'}}
 
   # only for PR