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Use the core client with explicit version globally

**What this PR does / why we need it**:
As mentioned in #49535 and #50605, we want to have a global replace to use core client with explicit version.

**Which issue this PR fixes**: fixes #49535 

**Special notes for your reviewer**:
The actual type of clientSet.Core() is already the same with clientSet.CoreV1(), so it should be safe replacement.
The places that clientSet.Core() are still in use are identified by IDE "find usages", and changes are made with one time global replace. Hopefully there will be none left after this PR merged.
Let me know if this PR is too big to review, I can split it into some smaller ones.

/cc @kubernetes/sig-api-machinery-pr-reviews 
/cc @k82cn @sttts 

**Release note**:

```release-note
none
```