Convert hello activities to sync #642

Job	Run time
build-lint-test (3.9, ubuntu-latest)	1m 4s
build-lint-test (3.9, macos-intel)	1m 19s
build-lint-test (3.9, macos-arm)	1m 20s
build-lint-test (3.9, windows-latest)	1m 16s
build-lint-test (3.12, ubuntu-latest)	1m 7s
build-lint-test (3.12, macos-intel)	1m 20s
build-lint-test (3.12, macos-arm)	1m 16s
build-lint-test (3.12, windows-latest)	1m 11s
	9m 53s

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