Problem:

DECIMAL columns in I_S must be explicitly set of some value.

I_S columns do not have `DEFAULT 0` (after MDEV-18918), so during
restore_record() their record fragments pointed by Field::ptr are
initialized to zero bytes 0x00.
But an array of 0x00's is not a valid binary DECIMAL value.
So val_decimal() called for such Field_new_decimal generated a warning
when seeing a wrong binary encoded DECIMAL value in the record.

Fix:

Explicitly setting INFORMATION_SCHEMA.PROCESSLIST.PROGRESS
to the decimal value of 0 if no progress information is available.