ci: do not re-run tests on master, use nightly instead

All tests are executed before merge and we allow only fast-forward
merges so it is pointless to re-run them again on merge commit.

Code coverage and OBS will be done on auto-synchornized nightly branch.
Status Job ID Name Coverage
  Build
canceled #159646
amd64 linux docker
build:clang:linux:amd64

00:00:07

canceled #159645
amd64 linux docker
build:linux:amd64

00:00:07

canceled #159647
amd64 linux docker allowed to fail
srpm

00:00:07

 
  Test
canceled #159654
amd64 linux docker
deckard:linux:amd64

canceled #159661
privileged
distro:epel-7

canceled #159660
privileged
distro:fedora-27

canceled #159653
docker
doc

canceled #159652
amd64 linux docker
installcheck:linux:amd64

canceled #159655
amd64 linux docker
installcheck:valgrind:linux:amd64

canceled #159649
docker
lint:c

canceled #159650
docker allowed to fail
lint:clang-scan-build

canceled #159648
docker
lint:lua

canceled #159658
amd64 linux docker
respdiff:iter:tcp:linux:amd64

canceled #159659
amd64 linux docker
respdiff:iter:tls:linux:amd64

canceled #159657
amd64 linux docker
respdiff:iter:udp:linux:amd64

canceled #159651
amd64 linux docker
test:linux:amd64

canceled #159656
amd64 linux docker
test:linux:amd64:valgrind

 
  Respdiff
canceled #159662
respdiff
respdiff:fwd-tls6-kresd.udp6

canceled #159663
respdiff
respdiff:fwd-udp6-kresd.udp6

canceled #159667
respdiff
respdiff:fwd-udp6-unbound.tcp6

canceled #159668
respdiff
respdiff:fwd-udp6-unbound.tls6

canceled #159666
respdiff
respdiff:fwd-udp6-unbound.udp6

canceled #159665
respdiff allowed to fail
respdiff:iter.tls6

canceled #159664
respdiff
respdiff:iter.udp6