Refactor diagnosis agent

[samplise]

What changes were proposed in this pull request?

Refactor diagnosis agent. The agent will observe the problems periodically.

Why are the changes needed?

Complete the framework that the agent could check if predefined problems happen.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Unit test

[codecov]

Codecov Report

Attention: Patch coverage is 95.30201% with 7 lines in your changes missing coverage. Please review.

Project coverage is 80.31%. Comparing base (1936f1d) to head (cf40a3c).
Report is 12 commits behind head on master.

Files with missing lines	Patch %	Lines
.../python/elastic_agent/diagnosis/diagnosis_agent.py	87.50%	4 Missing ⚠️
dlrover/python/diagnosis/common/diagnose_action.py	83.33%	1 Missing ⚠️
...n/inferenceoperator/metrics_collection_operator.py	95.45%	1 Missing ⚠️
...over/python/tests/test_diagnosis_data_collector.py	98.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1287      +/-   ##
==========================================
+ Coverage   80.19%   80.31%   +0.11%     
==========================================
  Files         218      222       +4     
  Lines       20336    20429      +93     
==========================================
+ Hits        16309    16408      +99     
+ Misses       4027     4021       -6     

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[BalaBalaYi]

LGTM