Remove unused playbook

lib/antora/templates/per-branch-antora-playbook.yml

@@ -1,37 +0,0 @@
-# The purpose of this Antora playbook is to build the docs in the current branch.
-antora:
-  extensions:
-  - '@antora/collector-extension'
-  - id: '@antora/atlas-extension'
-    require: '@antora/atlas-extension'
-    enabled: false
-  - require: '@springio/antora-extensions/tabs-migration-extension'
-    unwrap_example_block: always
-site:
-  title: Spring Authorization Server
-content:
-  sources:
-  - url: ./..
-    branches: HEAD
-    start_path: docs
-    worktrees: true
-asciidoc:
-  attributes:
-    page-stackoverflow-url: https://stackoverflow.com/tags/spring-authorization-server
-    hide-uri-scheme: '@'
-    page-pagination: ''
-    primary-site-url: https://docs.spring.io/spring-authorization-server/reference
-    tabs-sync-option: '@'
-  extensions:
-  - '@asciidoctor/tabs'
-  - '@springio/asciidoctor-extensions'
-  sourcemap: true
-urls:
-  latest_version_segment: ''
-runtime:
-  log:
-    failure_level: warn
-ui:
-  bundle:
-    url: https://github.com/spring-io/antora-ui-spring/releases/download/v0.3.6/ui-bundle.zip
-    snapshot: true