Automatic merge from submit-queue (batch tested with PRs 46734, 46810, 46759, 46259, 46771)
Improve code coverage for pkg/kubelet/images/image_gc_manager
**What this PR does / why we need it**:
#39559#40780
code coverage from 74.5% to 77.4%
**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**:
```release-note
NONE
```
af64e0b8c9