Remove MySQL support

src/Umbraco.Core/Persistence/DatabaseModelDefinitions/DefinitionFactory.cs

@@ -109,12 +109,6 @@ namespace Umbraco.Core.Persistence.DatabaseModelDefinitions
             var constraintAttribute = propertyInfo.FirstAttribute<ConstraintAttribute>();
             if (constraintAttribute != null)
             {
-                //Special case for MySQL as it can't have multiple default DateTime values, which
-                //is what the umbracoServer table definition is trying to create
-                if (sqlSyntax is MySqlSyntaxProvider && definition.TableName == "umbracoServer" &&
-                        definition.TableName.ToLowerInvariant() == "lastNotifiedDate".ToLowerInvariant())
-                    return definition;
-
                 definition.ConstraintName = constraintAttribute.Name ?? string.Empty;
                 definition.DefaultValue = constraintAttribute.Default ?? string.Empty;
             }