fix(metrics_summaries): Let summaries with only count through #14685

Job	Run time
Lint	6m 54s
Lint Rust Default Features	5m 16s
Test (macos-latest)	3m 6s
Test (windows-latest)	6m 54s
Test All Features (ubuntu-latest)	4m 1s
Test Python	1m 14s
Setup build metadata	1s
Integration Tests	13m 46s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	8m 5s
Build Docker Image (relay)	29s
Sentry-Relay Integration Tests	12m 48s
Publish Relay to DockerHub	0s
Upload build artifacts to gocd	0s
Publish Relay to GCR	0s
self-hosted-end-to-end	13m 1s
	1h 15m 35s

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