travis: Move exclusively to golang.
travis: Move exclusively to golang.

The travis tests were ignoring intermediate failures
in golang tests. For e.g., 'make gofmt' failing would
not fail the entire test. This commit takes this
opportunity to retire python checking and to move
exclusively to golang. This also will cause failures
if any intermediate step fails.

Signed-off-by: Gurucharan Shetty <a1872e333d0e52644f6125da2276530f7ebe5e77@ovn.org>

shettyg/ovn-kubernetes,shettyg/ovn-kubernetes,shettyg/ovn-kubernetes