Use remove_const after specs which set constants #376

Job	Run time
RuboCop	33s
specs (ubuntu, 3.1.6)	1m 35s
specs (ubuntu, 3.2.6)	1m 27s
specs (ubuntu, 3.3.7)	1m 28s
specs (ubuntu, 3.4.1)	1m 34s
specs (macos, 3.1.6)	1m 23s
specs (macos, 3.2.6)	1m 13s
specs (macos, 3.3.7)	1m 20s
specs (macos, 3.4.1)	1m 11s
specs (windows, 3.1.6)	4m 18s
specs (windows, 3.2.6)	4m 32s
specs (windows, 3.3.7)	4m 32s
specs (windows, 3.4.1)	4m 54s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 24s
	31m 24s

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