Migrate to connect-rpc #559

Job	Run time
Checks	3m 40s
Checks	3m 40s
Checks	3m 40s
Unit tests	1m 54s
Unit tests	1m 54s
Unit tests	1m 54s
Microbenchmarks	11m 32s
Microbenchmarks	14m 55s
Microbenchmarks	1h 0m 1s
Instrumentation tests (24, google_apis)	11m 0s
Instrumentation tests (24, google_apis)	11m 41s
Instrumentation tests (24, google_apis)	16m 19s
Codecov	0s
Codecov	0s
Codecov	8s
	2h 22m 18s

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