Remove old regression check #1073

Job	Run time
Rubocop	37s
Ruby 2.7 (Windows)	3m 45s
Ruby 2.6 (Windows)	3m 19s
Ruby 2.5 (Windows)	3m 40s
Ruby 2.4 (Windows)	4m 2s
Ruby 2.3 (Windows)	4m 50s
Ruby 2.2 (Windows)	3m 47s
Ruby 3.2	5m 2s
Ruby 3.1	5m 27s
Ruby 3.0	7m 23s
Ruby 2.7	7m 12s
Ruby 2.6	7m 7s
Ruby 2.5	9m 29s
Ruby 2.4	5m 42s
Ruby 2.3	5m 28s
Ruby 2.2	5m 37s
Ruby ruby-head	35s
Ruby jruby-9.2.13.0	3m 28s
Ruby 2.7 with diff-lcs 1.3	7m 6s
Ruby 2.7 with diff-lcs 1.4.3	5m 57s
Legacy Ruby Builds (2.1.9)	3m 1s
Legacy Ruby Builds (2.0)	3m 3s
Legacy Ruby Builds (1.9.3)	3m 10s
Legacy Ruby Builds (1.9.2)	5m 48s
Legacy Ruby Builds (1.8.7)	3m 51s
Legacy Ruby Builds (REE)	4m 0s
Legacy Ruby Builds (JRuby 1.7)	13m 23s
Legacy Ruby Builds (JRuby 1.7 1.8 mode)	13m 43s
Legacy Ruby Builds (JRuby 9.1.17.0)	15m 26s
	2h 44m 58s

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