Correct column names in logical record 0500 in get/read_bsrn

[AdamRJensen]

• Closes Issue in get/read_bsrn naming of variables in logical record 0500 #2835
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This PR fixes a bug in the column naming when requesting logical record 0500 data with the get/read_bsrn functions.

Specifically, the first two columns on the second lines in LR0500 do not contain any data and hence these two columns should be removed. Additionally, the first row lines do not contain data in the last four columns. Therefore, there needs to be six consequetive columns removed after unpacking the data. These columns are first named "empty" and then subsequently removd.