Mark any_instance proxy methods as private if they were private #881

Job	Run time
Ruby 2.7 (Windows)	2m 34s
Rubocop	28s
Ruby 2.6 (Windows)	3m 38s
Legacy Ruby Builds (2.1.9)	1m 12s
Ruby 2.5 (Windows)	2m 9s
Ruby 3.3	2m 56s
Legacy Ruby Builds (2.0)	1m 7s
Ruby 2.4 (Windows)	1m 49s
Ruby 3.2	2m 45s
Legacy Ruby Builds (1.9.3)	1m 17s
Ruby 2.3 (Windows)	1m 52s
Ruby 3.1	2m 45s
Legacy Ruby Builds (1.9.2)	2m 14s
Ruby 2.2 (Windows)	2m 22s
Ruby 3.0	2m 46s
Legacy Ruby Builds (1.8.7)	46s
Ruby 2.7	2m 58s
Legacy Ruby Builds (REE)	1m 0s
Ruby 2.6	2m 34s
Legacy Ruby Builds (JRuby 1.7)	3m 29s
Ruby 2.5	2m 31s
Legacy Ruby Builds (JRuby 1.7 1.8 mode)	45s
Ruby 2.4	2m 29s
Legacy Ruby Builds (JRuby 9.1.17.0)	4m 12s
Ruby 2.3	2m 31s
Ruby 2.2	2m 57s
Ruby ruby-head	1m 10s
Ruby jruby-9.2.13.0	6m 21s
Ruby 2.7 with diff-lcs 1.3	2m 51s
Ruby 2.7 with diff-lcs 1.4.3	3m 7s
	1h 11m 35s

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