Turn off DetDesc configuration when using DD4hep

This MR completely hides the DetDesc configuration and databases when in DD4hep mode, so that we can check that everything has been migrated. As a corollary, this is expected not to change anything in the normal platforms, but increase the number of failures in +dd4hep platforms.

I fixed as many tests as I could. Some tests still use DetDesc as they are meant to compare the two geometries while others are disabled as they cannot exist without DetDesc.

As discussed in !3461 (comment 5450094) and lhcb-datapkg/ParamFiles!47, ParticleTable.txt needs some more care as we are not going to take it from DetDesc anymore. For the time being I introduced a couple of copies of it to be able to run the tests (one could be removed with some massaging of the reference file).

Note also that 3 of the commits in this MR are minor fixes and could be merged independently.

/cc @jonrob @sponce @bcouturi @raaij @gligorov @rmatev @graven