feat(spooler): Implement backpressure mechanism based on atomics #15385

Job	Run time
Lint	3m 25s
Lint	3m 25s
Test All Features (ubuntu-latest)	3m 53s
Test All Features (ubuntu-latest)	3m 53s
Lint Rust Default Features	1m 25s
Lint Rust Default Features	1m 25s
Test (macos-latest)	2m 57s
Test (macos-latest)	2m 57s
Test (windows-latest)	5m 20s
Test (windows-latest)	5m 20s
Setup build metadata	1s
Setup build metadata	1s
Integration Tests	12m 12s
Integration Tests	11m 54s
Test Python	55s
Test Python	55s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	8m 0s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	8m 0s
Build Docker Image (relay)	42s
Build Docker Image (relay)	42s
Sentry-Relay Integration Tests	11m 48s
Sentry-Relay Integration Tests	11m 48s
Publish Relay to DockerHub	0s
Publish Relay to DockerHub	0s
Upload build artifacts to gocd	0s
Upload build artifacts to gocd	0s
Publish Relay to GCR	0s
Publish Relay to GCR	0s
self-hosted-end-to-end	13m 7s
self-hosted-end-to-end	13m 7s
	2h 7m 12s

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