MDEV-29159 Patch for MDEV-28918 introduces more inconsistency than it solves, breaks usability

1. Store assignment failures on incompatible data types now raise errors if:
- STRICT_ALL_TABLES or STRICT_TRANS_TABLES sql_mode is used, and
- IGNORE is not used

Otherwise, only a warning is raised and the statement continues.

2. Changing the error/warning test as follows:

-ERROR HY000: Illegal parameter data types inet6 and int for operation 'SET'
+ERROR HY000: Cannot cast 'int' as 'inet6' in assignment of `db`.`t`.`col`

so in case of a big table it's easier to see which column has the problem.
The new error text is also applied to SP variables.

sql/sql_table.cc

@@ -11084,7 +11084,7 @@ copy_data_between_tables(THD *thd, TABLE *from, TABLE *to,
       if (!(*ptr)->vcol_info)
       {
         bitmap_set_bit(from->read_set, def->field->field_index);
-        if ((*ptr)->check_assignability_from(def->field))
+        if ((*ptr)->check_assignability_from(def->field, ignore))
           goto err;
         (copy_end++)->set(*ptr,def->field,0);
       }