Remove dead or unnecessary methods/attributes

[st0012]

2 types of targets in this PR:

• Completely unused methods (outside of tests, ofc)
• Single-used or unnecessary methods. Like:

  def each_constant # :yields: constant
    @constants.each {|c| yield c}
  end

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[st0012]

These same test assertions actually appear in other tests like test_update_includes_with_colons as well. So we don't need to keep them here either.

[kou]

+1