Deprecate `ingester_metadata_streaming` config

[alanprot]

What this PR does:

This pull request removes the ingester_metadata_streaming flag and ensures metadata is always streamed.

Previously, metadata streaming was disabled by default, but streaming has proven stable with no drawbacks. Therefore, I'm proposing to remove this configuration and always stream metadata.

Which issue(s) this PR fixes: Fixes #

Checklist

• [ ] Tests updated
• [ ] Documentation added
• [ ] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]