Removed double comma for Multi Active Hashkey calculation

[tkirschke]

• Line 25 in hash_columns.sql would produce double commas, since there is also a comma outside the "if"-block, in line 36. This leads to a SQL Fail.
• Column names of Ghost Records in snowflake were not escaped
• Hash Input Columns, that are derived/prejoined columns, were not properly excluded, because the UPPER() mapping in stage_processing_macros.sql was not applied to both lists