Remove TIE-GCM load support for pysat.utils.load_netCDF4

[aburrell]

Is your feature request related to a problem? Please describe.
The location and name of the function to load netCDF data will soon change. This function is used by the UCAR TIE-GCM instrument in a direct call. At the moment, an if/else statement checks to see which call should be made.

Describe the solution you'd like
Not have if/else statements everywhere.

Describe alternatives you've considered
Adding a pysat version limit

Additional context
Eventually a pysat version limit will make sense, but for the moment, it's good to support any version of pysat 3.X.

[jklenzing]

This applies to sami2py and dineofs too.