use hasSlaveScripts label when requiring scripts

The Jenkins scripts are provided by integration/jenkins.git, often named
'slave scripts'.  This patch make some jobs relying on them with the
label hasSlaveScripts so we run them on slaves having the scripts.

Jobs updated:

	integration-jjb-config-yamllint
	integration-zuul-config-yamllint
	operations-puppet-pep8
	qa-browsertests-yamllint
	translatewiki-yamllint

Change-Id: Ic8b2d540fb1bb22307f8c488a85b2e4a6a740245