changed severity of G-3170 to blocker

because without proper default value the row does not
look like expected, it's likely a bug

Author: PhilippSalvisberg

docs/4-language-usage/3-dml-and-sql/1-general/g-3170.md

@@ -1,6 +1,6 @@
 # G-3170: Always use DEFAULT ON NULL declarations to assign default values to table columns if you refuse to store NULL values.
 
-!!! warning "Major"
+!!! bug "Blocker"
     Reliability
 
 !!! missing "Unsupported in db\* CODECOP Validators"