Changes:
- Use UIB8 based base imgae
- Use go-toolset from UBI8
Currently comet repo exists for rhel-8 based images, so to onboard to konflux easily we'll go ahead with rehl-8 image now. When comet repo for rhel-9 is configured, we'll switch to rehl-9 based images.
- Update Dockerfiles to use the ubi9 go-toolset images. For the
releaser image, this avoids downloading the go sdk as part of the
relase process.
- Add `build-container` make target for convenience.
- Update ci-operator build root to use rhel-9 golang 1.20 image for OCP
4.15
Signed-off-by: Adam Kaplan <adam.kaplan@redhat.com>