Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit d6958adb8002f8de738a43eb0bd561a4221f2dd9.
Revert "[maven-release-plugin] prepare release v0.8.0-incubating"

This reverts commit 3ffc9576faa8f98c90bc837655946368c3d1705e.