Data delivery: Remove `region` variable (but not dimension)

[agstephens]

From all spatially averaged files.

(Add in a must not exist rule in comp check).

[agstephens]

Examples:

LS1:

       int region(region) ;
              region:units = "1" ;
              region:standard_name = "region" ;
       char geo_region(region, string27) ;
              geo_region:units = "1" ;
              geo_region:long_name = "River Basin" ;

LS2:

       int region(region) ;
              region:units = "1" ;
              region:standard_name = "region" ;
       char geo_region(region, string24) ;
              geo_region:units = "1" ;
              geo_region:standard_name = "region" ;
              geo_region:long_name = "Administrative Region" ;