docs(gcs): remove note that multi object delete is not supported

[danielduhh]

Summary

XML Multi Object Delete is now GA for GCS.
Referece: https://docs.cloud.google.com/storage/docs/xml-api/post-bucket

Checklist

• [ x] Delete items not relevant to your PR
• [ x] URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• [ x] If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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