improve handling of edge cases related to source position at boundary where no/little MC is vailable.

[HansN87]

Injecting a source at -5.7 deg (at the edge of Northern Tracks even selection) yields the following non-descriptive error message:

[...]
File "/data/user/hmniederhausen/software/skyllh_v003p03_v1/skyllh/skyllh/core/parameters.py", line 1256, in _calc_floatD_and_intD
','.join(str(v) for v in value[np.invert(m)])))
ValueError: The following values are outside the range of the parameter grid "gamma": nan

A better way of handling this would be to require each analysis to provide a "safe" range / bounds for the source declination.

[chiarabellenghi]

Funny thing, I saw this very same non-descriptive error when using the publicdata_ps branch. But with public data, we don't have any specific declination constraints, and I was injecting right at the horizon (-0.01 deg).

The issue might be related to some bin edge issues.

[martwo]

For the IceCube internal KDE point-source analysis this issue was fixed with PR #182

For the public PS data this might still be an issue, because it uses a different signal generator class.