Automatic merge from submit-queue (batch tested with PRs 41134, 41410, 40177, 41049, 41313)

Refactored kubemark code into provider-specific and provider-independent parts [Part-3]

Fixes #38967
Applying final part of the changes in PR #39033 (which refactored kubemark code completely). The changes included in this PR are:

- Removed `test/kubemark/common.sh` and moved relevant parts of its code to the right places in start-kubemark/stop-kubemark scripts.
- Added DOCKER_REGISTRY, PROJECT, KUBEMARK_IMAGE_MAKE_TARGET variables to `/test/kubemark/cloud-provider-config.sh` to make the kubemark image push location variable wrt provider.
- Removed get-real-pod-for-hollow-node.sh as it doesn't seem to do anything useful.

@kubernetes/sig-scalability-misc @wojtek-t @gmarek