chore(fab): code cleanup for fab plugin removal (#5010)

Signed-off-by: Yi Cai <yicai@redhat.com>

Author: ciiay

.ci/pipelines/value_files/values_showcase.yaml

@@ -18,8 +18,6 @@ global:
     # an optional `pluginConfig` with plugin-specific backstage configuration, and an optional `disabled` flag to disable/enable a plugin
     # listed in `includes` files. It also includes an `integrity` field that is used to verify the plugin package [integrity](https://w3c.github.io/webappsec-subresource-integrity/#integrity-metadata-description).
     plugins:
-      - package: ./dynamic-plugins/dist/red-hat-developer-hub-backstage-plugin-global-floating-action-button
-        disabled: true
       - package: ./dynamic-plugins/dist/backstage-plugin-scaffolder-backend-module-github-dynamic
         disabled: false
       - package: ./dynamic-plugins/dist/backstage-plugin-catalog-backend-module-github-dynamic