Automatic merge from submit-queue
specify custom ca file to verify the keystone server
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**What this PR does / why we need it**:
Sometimes the keystone server's certificate is self-signed, mainly used for internal development, testing and etc.
For this kind of ca, we need a way to verify the keystone server.
Otherwise, below error will occur.
> x509: certificate signed by unknown authority
This patch provide a way to pass in a ca file to verify the keystone server when starting `kube-apiserver`.
**Which issue this PR fixes** : fixes#22695, #24984
**Special notes for your reviewer**:
**Release note**:
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860cae0933