Change CMAKE_BUILD_TYPE to RelWithDebInfo

At the moment, CTA in production is being built in Debug mode. This should eventually be switched to RelWithDebInfo for performance reasons. The only thing to be aware of is that optimisation flags enabled by RelWithDebInfo can expose bugs in the software (in particular functionality relying on undefined behaviour).

As such, we should first try and fix any SonarCloud issues that might be related to this. Once we are confident that we can make this change, we can simply change the build type in the arguments of the new build scripts (see #725 (closed)).

During the meeting, we mentioned we might keep preproduction in Debug mode and production in RelWithDebInfo. The danger with this is that potential bugs introduced by this might not be observed in preproduction. This is something to think about.