gitlab-runner: add `authenticationTokenConfigFile` #2038

Job	Run time
install-against-stable	4m 31s
install-flake-against-stable	3m 19s
install-flake-against-unstable	5m 0s
install-against-unstable	6m 5s
test-unstable	15m 16s
test-stable	18m 5s
	52m 16s

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