[enh] Make maxAccumulations configurable and add remove method for meters

[tjiuming]

Motivation:

1. Currently, a meter(COUNTER/GAUGE/HISTOGRAM, etc.) could only have 2000 children, which means it couldn't cover some situations (such as there are 10000 topics in a broker, and they all have a COUNTER named publish_messages_count).
2. For a meter, I think it should have a remove method to discard unused ACCUMULATIONS. (such as a user deletes a broker, so we need to remove it from publish_messages_count).

[linux-foundation-easycla[bot]]

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[tjiuming]

I'll fix the CI failures later if the PR is acceptable.

[github-actions[bot]]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions[bot]]

Closed as inactive. Feel free to reopen if this PR is still being worked on.