[DBMON-5536] collect index stats on replica set secondaries

[lu-zhengda]

What does this PR do?

Collect index stats metrics mongodb.collection.indexes.accesses.opsps on replica set secondary nodes. For sharded cluster, the index stats metrics are still only collected on mongos.

Motivation

Feature request: index stats on secondaries provide insights into read operations index usage targeting secondaries.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.15%. Comparing base (3a712b8) to head (e772eef).
Report is 15 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
confluent_platform	?
hive	?
hivemq	?
hudi	?
ignite	?
jboss_wildfly	?
kafka	?
mongo	93.15% <100.00%> (+0.23%)	⬆️
presto	?
solr	?
tomcat	?
weblogic	?

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