Deprecate multi-irb commands #2289

Job	Run time
ruby-versions / Generate Ruby versions	2s
vterm-yamatanooroti 2.7 (latest reline)	1m 19s
vterm-yamatanooroti 2.7	1m 14s
vterm-yamatanooroti 3.0 (latest reline)	49s
vterm-yamatanooroti 3.0	48s
vterm-yamatanooroti 3.1 (latest reline)	58s
vterm-yamatanooroti 3.1	59s
vterm-yamatanooroti 3.2 (latest reline)	46s
vterm-yamatanooroti 3.2	53s
vterm-yamatanooroti head (latest reline)	1m 38s
vterm-yamatanooroti head	49s
rake test 2.7 (latest reline)	45s
rake test 2.7	43s
rake test 3.0 (latest reline)	36s
rake test 3.0	27s
rake test 3.1 (latest reline)	32s
rake test 3.1	32s
rake test 3.2 (latest reline)	30s
rake test 3.2	34s
rake test head (latest reline)	31s
rake test head	35s
rake test truffleruby-head (latest reline)	5m 14s
rake test truffleruby-head	7m 39s
	28m 53s

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