Switch to defacto way to specify max_length

mathesar/api/serializers/shared_serializers.py

@@ -111,29 +111,24 @@ class NumberDisplayOptionSerializer(MathesarErrorMessageMixin, OverrideRootParti
     show_as_percentage = serializers.BooleanField(default=False)
     locale = serializers.CharField(required=False)
 
+
 def raise_if_duration_format_invalid(format):
     if 'z' in format.lower():
         raise serializers.ValidationError(
             "Duration column cannot contain timezone display format"
         )
 
-def raise_if_time_format_invalid(format):
-    if isinstance(format, str) and len(format) <= 255:
-        return
-    else:
-        raise serializers.ValidationError("Time format string not a string or longer than 255 characters.")
-
 
 class TimeFormatDisplayOptionSerializer(
     MathesarErrorMessageMixin,
     OverrideRootPartialMixin,
     serializers.Serializer
 ):
-    format = serializers.CharField(validators=[raise_if_time_format_invalid])
+    format = serializers.CharField(max_length=255)
 
 
 class DurationDisplayOptionSerializer(MathesarErrorMessageMixin, OverrideRootPartialMixin, serializers.Serializer):
-    format = serializers.CharField(validators=[raise_if_duration_format_invalid])
+    format = serializers.CharField(max_length=255, validators=[raise_if_duration_format_invalid])
 
 
 class DisplayOptionsMappingSerializer(