Deprecate multi-irb commands #2249

Job	Run time
ruby-versions / Generate Ruby versions	2s
vterm-yamatanooroti 2.7 (latest reline)	1m 16s
vterm-yamatanooroti 2.7	1m 3s
vterm-yamatanooroti 3.0 (latest reline)	51s
vterm-yamatanooroti 3.0	47s
vterm-yamatanooroti 3.1 (latest reline)	1m 7s
vterm-yamatanooroti 3.1	1m 3s
vterm-yamatanooroti 3.2 (latest reline)	57s
vterm-yamatanooroti 3.2	48s
vterm-yamatanooroti head (latest reline)	37s
vterm-yamatanooroti head	46s
rake test 2.7 (latest reline)	41s
rake test 2.7	41s
rake test 3.0 (latest reline)	29s
rake test 3.0	37s
rake test 3.1 (latest reline)	31s
rake test 3.1	29s
rake test 3.2 (latest reline)	25s
rake test 3.2	39s
rake test head (latest reline)	26s
rake test head	31s
rake test truffleruby-head (latest reline)	6m 44s
rake test truffleruby-head	5m 47s
	27m 17s

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