add HA dedupe functionality to docker dev environment

[aldernero]

What this PR does

This PR updates the microservers docker compose development environment so that it can more easily be used to test the functionality and changes to the HA tracker. Specifically it

• adds an option enable_ha_tracker to toggle the functionality
• when the above is enabled, 2 additional prometheii are started that scrape the memcache-exporter and load-generator and add the relevant cluster and replica labels required by the HA tracker.
• the two targets scraped for the HA tracker are now removed from the base prometheus scrape targets
• the relevant flags to enable HA tracking were added to the mimir config

I chose to use 2 smaller prometheii instead of having 2 prometheii that scrape all the targets to save on memory requirements.

Checklist

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