[v1.4] Fix conflict in camera subscriptions #3401

Job	Run time
alpine 3.11.6 (musl)	9m 51s
coverage (ubuntu-20.04)	4m 9s
Ubuntu/Debian packaging (Ubuntu 20.04)	8m 8s
ubuntu-18.04 (package, non-mavsdk_server)	6m 13s
ubuntu-20.04 (package, non-mavsdk_server)	5m 14s
linux-armv6	4m 5s
linux-armv7	4m 11s
linux-arm64	4m 0s
android-arm	7m 45s
android-arm64	8m 43s
android-x86	6m 17s
android-x86_64	6m 12s
linux-armv6-musl	14m 50s
linux-armv7l-musl	10m 32s
linux-arm64-musl	11m 28s
manylinux2010-x64	7m 42s
ios	11m 4s
ios_simulator	9m 58s
macOS	13m 31s
macOS-framework	14m 13s
fedora-34 (package, non-mavsdk_server)	5m 15s
fedora-35 (package, non-mavsdk_server)	5m 11s
ubuntu-20.04 (check style and docs)	4m 55s
ubuntu-20.04 (mavsdk, hunter)	4m 1s
ubuntu-20.04 (non-mavsdk_server, non-superbuild)	3m 58s
ubuntu-20.04 (proto check)	14m 47s
ubuntu-20.04 (mavsdk_server, superbuild)	9m 35s
Windows	15m 29s
iOS XCFramework	45s
	3h 52m 2s

Provide feedback