kafka replay speed: add support for metadata & source

[dimitarvdimitrov]

What this PR does

1. Parallelization based on:

   • The parallelStoragePusher now supports separate pushers for different write request sources (e.g., API, RULE) per tenant.
   • This is necessary because the ingester keep track of metrics based on the source of the request.
   • The tradeoff is that the config option for batch size isn't what it looks like - we have 2N batches per tenant, not the N that's configured.

2. Metadata Handling:

   • Added support for pushing metadata alongside time series data.
   • Metadata is distributed across shards in a round-robin fashion.

Which issue(s) this PR fixes or relates to

Fixes #

Checklist

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