feat: improve DaemonSet upgrade models check (#1869)

[huangchenzhao]

What type of PR is this?

/kind good-first-issue
/kind feature

What this PR does / why we need it:

Check upgrade models AdvancedRollingUpdate, OTA and AutoUpdate by using case-insensitive string judgment instead of using "==".

By introducing:

1. strings.ToLower(stringA) to entire small letters before models check.
2. strings.EqualFold(stringA, stringB) directly check models.

we can ignore the difference between upper and lower case before models check.

Which issue(s) this PR fixes:

Fixes #1869

[sonarcloud]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (d1a8b03) 52.13% compared to head (d70ea19) 52.18%.
Report is 2 commits behind head on master.

Files	Patch %	Lines
.../daemonpodupdater/daemon_pod_updater_controller.go	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1898      +/-   ##
==========================================
+ Coverage   52.13%   52.18%   +0.05%     
==========================================
  Files         172      172              
  Lines       20882    20882              
==========================================
+ Hits        10886    10898      +12     
+ Misses       9028     9017      -11     
+ Partials      968      967       -1     

Flag	Coverage Δ
unittests	52.18% <75.00%> (+0.05%)	⬆️

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[rambohe-ch]

/rerun

[rambohe-ch]

/lgtm