Remove `struct RData` deprecated by `struct RTypedData` #5879

Job	Run time
make (check, i686)	11m 56s
make (check, cppflags=-DVM_CHECK_MODE)	9m 6s
make (check, --enable-shared --enable-load-relative)	8m 9s
make (check, --disable-yjit)	7m 27s
make (test-bundled-gems)	19m 37s
make (check, ubuntu-24.04, capi)	10m 31s
make (test-bundler-parallel, 50)	23m 27s
make-ibm	0s
Ubuntu result	3s
	1h 30m 16s

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