Avoid service autostart misbehavior
Currently, both KF5 and KF6 versions of the service can be co-installed.
This is actually bad, as it postpones the problem from installation to runtime, i.e. the user is exposed to seemingly random behavior during service autostart.
The service is a unique DBus instance, just renaming the service file does not change that, and doing so introduces random behavior in case concurrent autostart of both versions is attempted.
Distributions should install either the KF5 or KF6 version (both are fully compatible). The service consists of the service file, the actual daemon (baloo_file) and the extractor helper (baloo_file_extractor).
For distributions insisting on not splitting up the package, building of the service can be disabled with a CMake option.