Adds metrics for client-side event emission and subscription #15830

Job	Run time
docker, python:3.9	5m 19s
Server Tests - python:3.9, postgres:14	3m 21s
docker, python:3.10	5m 15s
Server Tests - python:3.10, postgres:14	3m 17s
docker, python:3.11	4m 55s
Server Tests - python:3.11, postgres:14	3m 8s
docker, python:3.12	5m 22s
Server Tests - python:3.12, postgres:14	3m 41s
Server Tests - python:3.9, sqlite	5m 14s
Server Tests - python:3.10, sqlite	5m 3s
Server Tests - python:3.11, sqlite	4m 55s
Server Tests - python:3.12, sqlite	5m 17s
Client Tests - python:3.9, postgres:14	6m 58s
Client Tests - python:3.10, postgres:14	6m 49s
Client Tests - python:3.11, postgres:14	6m 12s
Client Tests - python:3.12, postgres:14	6m 50s
	1h 21m 36s

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