Skipped calculation of surfarea and dvdrhon in grid_file theta approach

[David Dickinson]

We calculate surfarea and dvdrhon at https://bitbucket.org/gyrokinetics/gs2/src/5856fed635bb3d858f34e5a44fe467948e2974c4/src/theta_grid.f90#lines-2461

but we return early from this method if no_geo_info is not set to .true. (which is the default option) https://bitbucket.org/gyrokinetics/gs2/src/5856fed635bb3d858f34e5a44fe467948e2974c4/src/theta_grid.f90#lines-2445

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These values aren’t really used in GS2 but they might be used elsewhere (e.g. trinity).