[GR-17457] Cleanup RubyLauncher and update comment #4631

Job	Run time
build jvm	6m 18s
lint	13m 13s
build native	13m 48s
ruby/spec on CRuby 3.0	3m 30s
ruby/spec on CRuby 3.1	3m 26s
ruby/spec on CRuby 3.2	2m 53s
specs :truffle	8m 49s
specs :language :core	12m 18s
specs :library :cext :security :command_line :tracepoint	9m 36s
test integration	11m 18s
fast specs	2m 17s
test native	3m 18s
run MRI tests on native	13m 26s
	1h 44m 10s

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