Revert `semtype changes` #8936

Job	Run time
Build Ballerina Lang	7m 15s
Build Ballerina Distribution	1h 10m 38s
Build Stdlib Level (1)	4m 25s
Build Stdlib Level (2)	14m 10s
Build Stdlib Level (3)	8m 49s
Build Stdlib Level (4)	16m 50s
Build Stdlib Level (5)	42m 9s
Build Stdlib Level (6)	25m 4s
Build Stdlib Level (7)	34m 6s
Build Stdlib Level (8)	1h 25m 13s
Build Stdlib Level (9)	4m 38s
	5h 13m 17s

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