schema validation: Teradata NUMBER is read as float64 instead of decimal

[nj1973]

Example columns:

,   col_dec_20      NUMBER(20)
,   col_dec_38      NUMBER(38)
,   col_dec_10_2    NUMBER(10,2)

DVT schema validation is reading these as float64. They should be decimal(20), decimal(38) and decimal(10,2).

When this is fixed we need to update integration test in test_teradata.py to use the correct types in allow list, search for "issue-838" in the file.

We also see column validation for Teradata NUMBER to BigQuery NUMERIC validations fail with:

TypeError: unsupported operand type(s) for -: 'decimal.Decimal' and 'float'

I suspect this will also be fixed by the same action as schema validation. Again search for "issue-838" in test_teradata.py to enable column validations.