Revert `semtype changes` #8932

Job	Run time
Build Ballerina Lang	7m 24s
Build Ballerina Distribution	11m 26s
Build Stdlib Level (1)	1m 20s
Build Stdlib Level (2)	1m 40s
Build Stdlib Level (3)	1m 54s
Build Stdlib Level (5)	1m 46s
Build Stdlib Level (4)	2m 6s
Build Stdlib Level (6)	2m 12s
Build Stdlib Level (7)	1m 58s
Build Stdlib Level (8)	11m 24s
Build Stdlib Level (9)	3m 25s
	46m 35s

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