Use root @springio/antora-extensions for docs build

See more info in: https://github.com/spring-io/antora-extensions

(cherry picked from commit 53b9469)

src/reference/antora/antora-playbook.yml

@@ -1,18 +1,9 @@
 antora:
-  extensions:
-    - '@springio/antora-extensions/partial-build-extension'
-    - # atlas-extension must be before latest-version-extension so the latest versions are applied to imported versions
-    - '@antora/atlas-extension'
-    - require: '@springio/antora-extensions/latest-version-extension'
-    - require: '@springio/antora-extensions/inject-collector-cache-config-extension'
-    - '@antora/collector-extension'
-    - require: '@springio/antora-extensions/root-component-extension'
-      root_component_name: 'amqp'
-      # FIXME: Run antora once using this extension to migrate to the Asciidoc Tabs syntax
-      # and then remove this extension
-    - require: '@springio/antora-extensions/tabs-migration-extension'
-      unwrap_example_block: always
-      save_result: true
+  antora:
+    extensions:
+      - require: '@springio/antora-extensions'
+        root_component_name: 'amqp'
+
 site:
   title: Spring AMQP
   url: https://docs.spring.io/spring-amqp/reference/