Revert `semtype changes` #8935

Job	Run time
Build Ballerina Lang	7m 56s
Build Ballerina Distribution	22m 27s
Build Stdlib Level (2)	12m 53s
Build Stdlib Level (1)	4m 21s
Build Stdlib Level (4)	15m 51s
Build Stdlib Level (3)	9m 1s
Build Stdlib Level (5)	22m 43s
Build Stdlib Level (6)	22m 43s
Build Stdlib Level (7)	22m 42s
Build Stdlib Level (9)	4m 43s
Build Stdlib Level (8)	22m 30s
	2h 47m 50s

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