Remove the deprecated Bignum and Fixnum constants. #4393

Job	Run time
build jvm	6m 38s
ruby/spec on CRuby 3.0	3m 22s
build native	14m 27s
lint	12m 39s
ruby/spec on CRuby 3.1	3m 20s
ruby/spec on CRuby 3.2	2m 50s
fast specs	1m 50s
specs :truffle	8m 50s
test integration	9m 6s
specs :language :core	11m 9s
specs :library :cext :security :command_line :tracepoint	8m 56s
run MRI tests on native	14m 4s
test native	4m 37s
	1h 41m 48s

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