Improve e2e labels matters

[hj-johannes-lee]

We currently have plain text form labels and that is not supported by -label-filter.
Since -label-filter looks cleaner and straightforward than mixing -focus and -skip, it is required to change as follows if we want to use -label-filter.

• update test/e2e/<dev>/<dev>.go files to use ginkgo.Label() instead of plain text.
• update Makefile to use -label-filter
• update .github/workflows/lib-e2e.yaml