:bug: Fixed exposure schema validity test err messages

[pushrbx]

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Problem: When the exposure schema validity test fails for data type mismatches, it doesn't show what was the received type. Example:

different data type for the column ASOF_DATE DATE vs 

This PR fixes that, and adds a new test for it.

Note:

• The added test can be also merged together with test_exposure_schema_validity_correct_columns_and_invalid_type test, but I wasn't sure.