Automatic merge from submit-queue (batch tested with PRs 63603, 63557, 62015). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Clean up equiv cache with a simple implementation instead of LRU

**What this PR does / why we need it**:

The original version of equiv cache use pod hash as cache key, also, the predicate order is not fixed. So I used a LRU cache to improve hit rate.

While now we've already refactored it to use predicates as keys, and its order was also fixed in scheduler, we can use a simplest cache instead now.

**Special notes for your reviewer**:

The question is brought up by @misterikkit

**Release note**:

```release-note
NONE
```