[GR-18163] Share a Fiber as soon as it's created and sharing is enabled #4926

Job	Run time
lint	14m 32s
build jvm	6m 23s
build native	13m 18s
ruby/spec on CRuby 3.0	3m 30s
ruby/spec on CRuby 3.1	3m 50s
ruby/spec on CRuby 3.2	3m 0s
fast specs	2m 6s
test integration	9m 40s
specs :truffle	14m 49s
specs :language :core	13m 0s
specs :library :cext :security :command_line :tracepoint	9m 39s
run MRI tests on native	15m 44s
test native	3m 7s
	1h 52m 38s

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