fix: safe unregister SystemEventsBroadcastReceiver #6940

Job	Run time
system-test (sentry-samples-spring-boot-opentelemetry, true, false)	7m 37s
system-test (sentry-samples-spring-boot-4-opentelemetry, true, true)	8m 0s
system-test (sentry-samples-spring-boot-webflux-jakarta, false, true)	6m 16s
system-test (sentry-samples-console, false, true)	2m 16s
system-test (sentry-samples-spring-boot-jakarta-opentelemetry, true, false)	9m 2s
system-test (sentry-samples-spring-boot-4, false, true)	7m 8s
system-test (sentry-samples-spring-boot-opentelemetry, true, true)	8m 13s
system-test (sentry-samples-spring-boot-webflux, false, true)	6m 26s
system-test (sentry-samples-spring-boot-opentelemetry-noagent, false, true)	7m 44s
system-test (sentry-samples-log4j2, false, true)	2m 36s
system-test (sentry-samples-spring-boot, false, true)	6m 42s
system-test (sentry-samples-spring-boot-jakarta-opentelemetry-noagent, false, true)	7m 24s
system-test (sentry-samples-logback, false, true)	2m 16s
system-test (sentry-samples-spring-boot-4-webflux, false, true)	5m 35s
system-test (sentry-samples-jul, false, true)	2m 16s
system-test (sentry-samples-spring-jakarta, false, true)	5m 4s
system-test (sentry-samples-spring-boot-jakarta, false, true)	8m 15s
system-test (sentry-samples-spring-boot-jakarta-opentelemetry, true, true)	8m 42s
system-test (sentry-samples-spring-boot-4-opentelemetry, true, false)	7m 52s
system-test (sentry-samples-spring, false, true)	4m 27s
system-test (sentry-samples-spring-7, false, true)	5m 27s
	2h 9m 18s

Provide feedback