[cherry-pick][release-1.12]Code clean for backup cmd client. (#6750)

[blackpiglet]

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Cherry-pick #6750 into release-1.12.

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file or added /kind changelog-not-required as a comment on this pull request.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

Merging #6912 (0eaf14e) into release-1.12 (c415fd4) will increase coverage by 0.03%.
The diff coverage is 85.71%.

@@               Coverage Diff                @@
##           release-1.12    #6912      +/-   ##
================================================
+ Coverage         60.34%   60.38%   +0.03%     
================================================
  Files               246      246              
  Lines             26232    26228       -4     
================================================
+ Hits              15830    15837       +7     
+ Misses             9286     9277       -9     
+ Partials           1116     1114       -2     

Files	Coverage Δ
pkg/controller/backup_controller.go	61.25% <100.00%> (ø)
pkg/controller/backup_deletion_controller.go	49.87% <100.00%> (ø)
pkg/cmd/cli/backup/create.go	67.04% <50.00%> (+0.63%)	⬆️

... and 1 file with indirect coverage changes

[shubham-pampattiwar]

@blackpiglet This PR has some extra changes too other than the cherry-pick ones.

[blackpiglet]

@shubham-pampattiwar
Yeah, there was a Github action that reported some code-spell errors. The additional changes are used to address these issues.