Specifies the latest image's tag as the branch name

Created by: pixiake

Signed-off-by: feng guofeng@yunify.com

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

The latest image's tag is named as the branch name to ensure that the latest image's tag is consistent with the branch name.

Does this PR introduced a user-facing change?

NONE