Automatic merge from submit-queue (batch tested with PRs 60430, 60115, 58052, 60355, 60116). 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>.
Add Garbage Collector e2e conformance tests
**What this PR does / why we need it**:
The garbage collector is a core component of kubernetes and needs to be tested by conformance, so its functionality can be relied on in any kubernetes environment.
As we can see in [testgrid](https://k8s-testgrid.appspot.com/sig-api-machinery#gce), the garbage collector tests being promoted by this PR are consistently passing. And the intention to promote them to conformance tests was laid out by [this document](https://docs.google.com/document/d/1h2S9ff9N-4MKqfayE3A8TqjD_qIwuND_dAhOAJFxYS0)
**Special notes for your reviewer**:
The last two tests in this file are not added as conformance tests because they involve beta features (custom resources and cronjobs), and conformance tests are only allowed for features in GA.
**Release note**:
```release-note
New conformance tests added for the Garbage Collector
```
Automatic merge from submit-queue. 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>.
Combine downward api e2e test cases.
**What this PR does / why we need it**:
This will reduce one loop of create/delete pod. Hope it can save some test time.
**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
```
This test creates a golden list of existing conformance tests. Efforts
to add or remove conformance tests will require you to rebuild the
golden list, and changes to the golden list will be reviewed by
sig-architecture.
Davanum Srinivas