Update the CA docker image used for e2e test (#1146)
Update the CA docker image used for e2e test (#1146)

Automatic merge from submit-queue

Update the CA docker image used for e2e test

Also make the `--mixer` and `--ca` CLI options consistent. Previously
`--mixer` takes the full docker image URI but `--ca` only accepts an
image tag. After this PR, both options take the full docker image URI.

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

**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**:

```
NONE
```
/cc @andraxylia 
/cc @wattli 
/cc @kyessenov
vadimeisenbergibm/pilot,vadimeisenbergibm/pilot,istio/old_pilot_repo,istio/old_pilot_repo,istio/old_pilot_repo,vadimeisenbergibm/pilot