[v2.12 BACKPORT] core: ignore no known remotes #4172

Job	Run time
ubuntu-20.04 (mavsdk, hunter)	1s
ubuntu-20.04 (mavsdk_server, superbuild)	1s
ubuntu-22.04 (mavsdk_server, superbuild)	1s
coverage (ubuntu-20.04)	1s
alpine 3.19.0 (musl)	1s
Ubuntu/Debian packaging (Ubuntu 20.04)	1s
ubuntu-20.04 (package, non-mavsdk_server)	1s
android-arm	1s
linux-armv6	1s
ubuntu-22.04 (package, non-mavsdk_server)	1s
linux-armv6-musl	1s
android-arm64	1s
linux-armv7	1s
android-x86	1s
linux-armv7l-musl	1s
linux-arm64	1s
android-x86_64	1s
linux-arm64-musl	1s
linux-arm64-lts	1s
ios	1s
ios_simulator_x64	1s
ios_simulator_arm64	1s
macOS x64	1s
ubuntu-20.04 (non-mavsdk_server, non-superbuild)	1s
ubuntu-22.04 (style and proto check)	1s
macOS arm64	1s
macOS framework x64	1s
Windows	1s
macOS framework arm64	1s
iOS XCFramework	1s
	30s

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