C3 images/tags wot CP8+ are still referring to the old naming/tag scheme, images are not found

For CP8.0/8.1 we are still referencing the old pre-CP8 C3 images - e.g.:
```
image:
application: confluentinc/cp-enterprise-control-center:8.1.0
init: confluentinc/confluent-init-container:3.1.0
```
I think this should be changed to the current C3-NG images:
```
image:
application: confluentinc/cp-enterprise-control-center-next-gen:2.3.0
init: confluentinc/confluent-init-container:3.1.0
```

No file or test is named; start by searching the repository for the old cp-enterprise-control-center:8.1.0 reference and related CP8.0/8.1 image tags. Done means the affected examples use the current C3-NG application image and retain the expected init image tag, with image references resolving successfully.

Written by the indexing model from the issue text.