Remove remaining references to spring-cloud-function-deployer

Describe the bug
The spring-cloud-function-deployer module was disabled in f96cd52e54b28b675458f743c8ed08cb4273004b and removed in 32444f17, and is thus no longer published (since 5.0.0-M2), however there are remaining references that cause confusion:

• The official documentation still recommends it, as per docs/modules/ROOT/pages/spring-cloud-function/deploying-a-packaged.adoc,
• spring-cloud-function-dependencies still manages its version,
• spring-cloud-function-samples still uses it and cannot be built,
• and the module is still commented out in the main pom.xml.

docs/modules/ROOT/pages/spring-cloud-function/deploying-a-packaged.adoc、spring-cloud-function-dependencies/pom.xml、spring-cloud-function-samples/function-sample-cloudevent-stream/pom.xml、および pom.xml 内のコメントアウトされたモジュールエントリから着手してください。spring-cloud-function-deployer への残りの参照を削除し、ドキュメントに記載されたデプロイ手順を更新して、影響を受けるサンプルを削除されたモジュールなしでビルドできることを確認してください。