[ruby/prism] Remove `Prism.lex_ripper` #742

Job	Run time
make (check, ubuntu-24.04, capi)	10m 29s
make (check, cppflags=-DVM_CHECK_MODE)	9m 9s
make (check, i686)	12m 4s
make (check, --disable-yjit)	8m 1s
make (test-bundler-parallel, 50)	23m 24s
make (test-bundled-gems)	20m 13s
ruby-bench (--warmup=1 --bench=1 --excludes=lobsters)	16m 36s
make (check, --enable-shared --enable-load-relative)	7m 59s
make-ibm	0s
Ubuntu result	3s
	1h 47m 58s

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