For some printer definitions the `machine_gcode_flavor` was entered incorrectly (the display name was used rather than the flavor-key). Previously in combo boxes the flavour would default to the first key (which is "marlin"). Due to recent changes we will not default anymore to the first option, but instead show nothing. By changing the flavor to the correct key the flavors will show up correctly again.
CURA-10374
Unsure whether this is necessary, but we decided to do this to make
the evaluation logically equivalent to the existing code currently
in master.
CURA-6711
In profiles that overwrite the support infill density, also keep it 0% for tree support.
Except PVA profiles. Those are probably better off with their normal infill density.
Fixes#5297.