Automatic merge from submit-queue (batch tested with PRs 48481, 48256)

Refactor: pkg/util into sub-pkgs

**What this PR does / why we need it**:
- move code in pkg/util into sub-pkgs
- delete some unused funcs

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #15634

**Special notes for your reviewer**:
This is the final work of #15634. It will close that issue.
/cc @thockin 

**Release note**:

```release-note
NONE
```