[GR-18163] Fix rb_str_locktmp() and rb_str_unlocktmp() to accept Stri… #5277

Job	Run time
lint	15m 27s
build jvm	6m 44s
ruby/spec on CRuby 3.1	1m 55s
build native	14m 6s
ruby/spec on CRuby 3.2	3m 2s
ruby/spec on CRuby 3.3	2m 59s
ruby/spec on CRuby 3.4	3m 37s
fast specs	1m 38s
test integration	9m 48s
specs :truffle	15m 9s
specs :language :core	12m 38s
specs :library :cext :security :command_line :tracepoint	9m 35s
test native	3m 40s
run MRI tests on native	18m 20s
	1h 58m 38s

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