Enable more tests now that TruffleRuby supports pattern matching

[eregon]

I also looked at the remaining occurences of truffleruby in the repo.
The remaining ones are still needed (e.g. to skip slow & Ripper-transient tests).

I also found

syntax_tree/lib/syntax_tree/language_server.rb

Lines 171 to 174 in 43ca866

	# This is a small module that effectively mirrors pattern matching. We're
	# using it so that we can support truffleruby without having to ignore the
	# language server.
	module Request

Which could use Ruby pattern matching again if desired.

[kddnewton]

This is now done effective spy through other PRs. Thanks!