We may not need the filter variables.name sections in obs filters

[guoqing-noaa]

Adapted from Additional QC Filter Options:

By default, filters are applied to all observations of the variables specified in the filter variables list (or if this list is not present, all simulated variables).

Since RDASApp limits each observers to one types and one variables of observations (such as t133, uv133, q133, etc), I think we don't need to add the following section into the obs filters (currently we only add it in some of the filters, which is not consistent):

           filter variables:
           - name: airTemperature

Correct me if I am wrong. @SamuelDegelia-NOAA @HuiLiu-NOAA

[HuiLiu-NOAA]

You are right. Just an issue of some more "clarity"?