Reduce test pend truffleruby

[tompng]

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[st0012]

5 less pends, this is awesome 🎉

[st0012]

cc @nirvdrum

[tompng]

The pended test was failing before mostly because the error message of SyntaxError is different in truffleruby.
IRB uses SyntaxError#message to check the code termination by Regexp.

irb/lib/irb/ruby-lex.rb

Lines 304 to 318 in 6269138

	rescue SyntaxError => e
	case e.message
	when /unterminated (?:string|regexp) meets end of file/
	# "unterminated regexp meets end of file"
	#
	# example:
	# /
	#
	# "unterminated string meets end of file"
	#
	# example:
	# '
	return :recoverable_error
	when /syntax error, unexpected end-of-input/
	# "syntax error, unexpected end-of-input, expecting keyword_end"

In the recent refactor, IRB's reliance to SyntaxError#message is reduced.
In show-source command, it is changed to only check if the code is syntax valid or not.
This is why these pend can be removed now.