Skip integration tests in core CI #2356

Job	Run time
ruby-versions / Generate Ruby versions	3s
rake test 2.7 (latest reline)	45s
rake test 2.7	50s
rake test 3.0 (latest reline)	41s
rake test 3.0	34s
rake test 3.1 (latest reline)	33s
rake test 3.1	30s
rake test 3.2 (latest reline)	43s
rake test 3.2	42s
rake test head (latest reline)	33s
rake test head	29s
rake test truffleruby-head (latest reline)	8m 13s
rake test truffleruby-head	6m 44s
vterm-yamatanooroti 2.7 (latest reline)	1m 14s
vterm-yamatanooroti 2.7	1m 27s
vterm-yamatanooroti 3.0 (latest reline)	50s
vterm-yamatanooroti 3.0	40s
vterm-yamatanooroti 3.1 (latest reline)	46s
vterm-yamatanooroti 3.1	1m 15s
vterm-yamatanooroti 3.2 (latest reline)	56s
vterm-yamatanooroti 3.2	58s
vterm-yamatanooroti head (latest reline)	41s
vterm-yamatanooroti head	51s
	30m 58s

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