Turn on concurrent set deletions in sweep thread #12793

Job	Run time
ruby-bench (--warmup=1 --bench=1)	14m 51s
make (check, --enable-shared --enable-load-relative)	5m 29s
make (test-bundler-parallel, 50)	23m 11s
make (test-bundled-gems)	19m 45s
make (check, i686)	3m 15s
make (check, cppflags=-DVM_CHECK_MODE)	5m 1s
make (check, --disable-yjit)	5m 10s
make (check, ubuntu-24.04, capi)	4m 49s
make-ibm	0s
Ubuntu result	2s
	1h 21m 33s

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