Stellar grid_uid correction

for older meter entries (in the dataset, thoughs created on or before 2023-05-11), NULL grid_uid values are incorrectly assigned a string value of "None_None".

UPDATE data_meters
SET grid_uid =
        CASE WHEN grid_uid = 'None_None'
            THEN NULL
            ELSE grid_uid
        END
;

run as one-off?