Optimize makefile

[cheyang]

Ⅰ. Describe what this PR does

Ⅱ. Does this pull request fix one issue?

fixes #1344

Ⅲ. List the added test cases (unit test/integration test) if any, please explain if no tests are needed.

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #1343 (3f1dd5a) into master (ab54f1e) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1343   +/-   ##
=======================================
  Coverage   70.48%   70.48%           
=======================================
  Files         221      221           
  Lines       12122    12122           
=======================================
  Hits         8544     8544           
  Misses       2659     2659           
  Partials      919      919           

Impacted Files	Coverage Δ
pkg/utils/kubeclient/exec.go	25.97% <ø> (ø)
pkg/webhook/certificate_builder.go	79.54% <100.00%> (ø)

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