Add tests to confirm observable counter aggregation bug #4202

Job	Run time
coverage	8m 17s
docs	5m 54s
external-types (opentelemetry)	1m 2s
cargo-deny	27s
external-types (opentelemetry-sdk)	1m 13s
lint	20m 30s
msrv	4m 12s
non-default-examples (opentelemetry-otlp/examples/external-otlp-grpcio-async-std)	5m 28s
non-default-examples (opentelemetry-otlp/examples/basic-otlp)	43s
test (stable)	17m 23s
test (beta)	17m 1s
	1h 22m 10s

Provide feedback