[INLONG-5428][Agent] Abstract metrics interface to be easier to extend

[pocozh]

Prepare a Pull Request

(Change the title refer to the following example)

• [INLONG-5428][Agent] Abstract metrics interface to be easier to extend

(The following XYZ should be replaced by the actual GitHub Issue number)

• Fixes [Improve][Agent] Abstract metrics interface to be easier to extend #5428

Modifications

• using metric template in inlong-common
• modify metric config in agent.properties
• support different metric listeners at the same time
• remove unused classes

Verifying this change

(Please pick either of the following options)

• This change is a trivial rework/code cleanup without any test coverage.

• This change is already covered by existing tests, such as:
  (please describe tests)

• This change added tests and can be verified as follows:

  (example:)

  • Added integration tests for end-to-end deployment with large payloads (10MB)
  • Extended integration test for recovery after broker failure

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a follow-up issue for adding the documentation

[luchunliang]

LGTM