Simplify long tests to only test target image rather than back to base image.

Removes verification of base image (dev channel) and instead re-updates to same image.  Our checking of changing kernel partitions should make a good test.  I think we're picking up bigs on old images and we don't really want to be testing that.

Change-Id: I4075d5c36eb190e4f037f05b40b032698dcd5c42

TEST=Ran ctest with x86-generic.

Review URL:
1 file changed