WIP: [Rhythm] Full RF1 read path

[mdisibio]

What this PR does:
I believe these are the changes needed to migrate the backend read path to RF1. New config options rf1_after which is a timestamp, after that only blocks with rf==1 are included in searches and trace by ID lookups. And an option to discontinue flushes to object storage from the ingesters.

How each api is handled:

Search: the frontend determines the blocks:

query_frontend:
  search:
    rf1_after: "2024-12-18T00:00:00Z"

Trace lookup: the querier determines the blocks:

querier:
  trace_by_id:
    rf1_after: "2024-12-18T00:00:00Z"

Tags: this is actually not filtering on replication factor, so no changes needed
Metrics: already limited to rf1 blocks

The migration path:

• Enable kafka ingest, block-builder, etc. It is now flushing RF1 blocks.
• Grace period for monitoring and validation
• Set rf1_after to move the read path over to the new RF1 blocks (recent searches/tags/tracelookups are still directed at ingesters)
• Grace period for monitoring and validation
• Disable flushes on ingesters

Note: Global config is non-trivial due to Tempo's modular setup, so this adds redundant config in multiple places. Not ideal.

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]

[mapno]

Nice, so close to RF1 🚀

[mapno]

We need to mark blocks flushed or change some logic so complete blocks are cleared at some point.