Shorten the release job exectuion time on travis
Shorten the release job exectuion time on travis

To avoid running into the global timeout on travis, only do necessary
steps to perform a release. Checking if `make generate` and `make`
changes any artifacts is not necessary. It is also not necessary to run
unit tests on the tag.

Signed-off-by: rmohr <6da0130c5aeef94e5bbaabadbf8017270be25c64@redhat.com>

stu-gott/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt