Summary:
Sticky connections were introduced as a new metric in D40484, but were left out from being published to the prometheus endpoint. This patch pushes the same information to the prometheus-metrics endpoint in addition to the pre-existing connections endpoint.

Jira: DB-15041

Test Plan:
Jenkins: enable connection manager, all tests

Verify that sticky conn metrics are available on prometheus endpoint on a local cluster

Reviewers: skumar, mkumar, devansh.saxena, vpatibandla

Reviewed By: mkumar, devansh.saxena

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D41484