Automatic merge from submit-queue (batch tested with PRs 45239, 45230)
Create a single CA for both client and server certs
**What this PR does / why we need it**:
The following test:
"Certificates API [It] should support building a client with a CSR"
fails with local-up-cluster, but works in the existing CI jobs. This
is because the other CI jobs use a single CA cert while local-up-cluster
can use 2 different sets of CA(s). We need a way to mimic the other
CI jobs (or alternatively change everything to have separate CA's). Just
updating local-up-cluster with a flag seems to be the easy route.
**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
```
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