enhancement: remove some client global vars

[rambohe-ch]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind enhancement

What this PR does / why we need it:

remove pkg/client and some global vars.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

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In response to this:

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind enhancement

What this PR does / why we need it:

remove pkg/client and some global vars.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

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[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rambohe-ch

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[YTGhost]

@rambohe-ch Please fix ci error.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
1.2% Duplication

[codecov]

Codecov Report

Merging #1655 (243d7dc) into master (96c32a7) will increase coverage by 0.22%.
The diff coverage is 0.00%.

❗ Current head 243d7dc differs from pull request most recent head 254c36a. Consider uploading reports for the commit 254c36a to get more accurate results

@@            Coverage Diff             @@
##           master    #1655      +/-   ##
==========================================
+ Coverage   52.24%   52.47%   +0.22%     
==========================================
  Files         155      155              
  Lines       17657    17536     -121     
==========================================
- Hits         9225     9202      -23     
+ Misses       7605     7509      -96     
+ Partials      827      825       -2     

Flag	Coverage Δ
unittests	52.47% <0.00%> (+0.22%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
.../daemonpodupdater/daemon_pod_updater_controller.go	29.80% <ø> (+0.29%)	⬆️
pkg/controller/raven/gateway/gateway_controller.go	22.69% <0.00%> (ø)
...ntroller/yurtappdaemon/yurtappdaemon_controller.go	19.47% <0.00%> (ø)
pkg/controller/yurtappset/yurtappset_controller.go	47.08% <0.00%> (+0.41%)	⬆️
...ntroller/yurtstaticset/yurtstaticset_controller.go	42.02% <0.00%> (-0.13%)	⬇️

... and 4 files with indirect coverage changes

[YTGhost]

/lgtm