Add cpu usage metric of the controller

[JiuyunZhao]

What this PR does / why we need it:

1. Add cpu usage metric of the controller.
2. Delete unused code.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Release note:

[codecov[bot]]

Codecov Report

Merging #919 (0cc17b8) into master (6729541) will increase coverage by 0.00%. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #919   +/-   ##
=======================================
  Coverage   71.16%   71.16%           
=======================================
  Files         182      182           
  Lines       21931    21918   -13     
  Branches     3343     3343           
=======================================
- Hits        15607    15598    -9     
+ Misses       5268     5261    -7     
- Partials     1056     1059    +3     

Impacted Files	Coverage Δ
delfin/api/schemas/storage_capabilities_schema.py	100.00% <ø> (ø)
delfin/drivers/fake_storage/__init__.py	94.41% <ø> (-1.02%)	:arrow_down:
...dulers/telemetry/performance_collection_handler.py	90.27% <ø> (ø)
delfin/utils.py	28.61% <ø> (-0.42%)	:arrow_down: