Making Vector default implementation for generated code #2318

Job	Run time
conformance	1m 52s
build (2_12, e2e)	3m 33s
build (2_12, test)	11m 33s
build (2_13, e2e)	4m 13s
build (2_13, test)	11m 32s
build (3, e2e)	4m 32s
build (3, test)	11m 30s
build (2_12, examples_and_formatting)	2m 40s
build (2_13, scala3_compat_test)	8m 32s
build (3, scala3_compat_test)	8m 36s
ci-passed	1s
	1h 8m 34s

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