fix(eap): handle null attribute values (#6837)

Closes https://github.com/getsentry/eap-planning/issues/169
- add null handling in results
- make casted fields nullable
- refactor

Note: do not merge until sentry-side is updated to account for the new
is_null boolean

Author: davidtsuk

.vscode/settings.json

@@ -67,4 +67,5 @@
   "python.testing.pytestArgs": ["tests"],
   "python.analysis.autoImportCompletions": true,
   "mypy-type-checker.args": ["--strict"]
+
 }

snuba/datasets/configuration/events_analytics_platform/entities/eap_spans.yaml

@@ -73,21 +73,6 @@ query_processors:
       time_parse_columns:
         - start_timestamp
         - end_timestamp
-  - processor: OptionalAttributeAggregationTransformer
-    args:
-      attribute_column_names:
-        - attr_num
-      aggregation_names:
-        - sum
-        - count
-        - avg
-        - avgWeighted
-        - max
-        - min
-        - uniq
-      curried_aggregation_names:
-        - quantile
-        - quantileTDigestWeighted
   - processor: HashBucketFunctionTransformer
     args:
       hash_bucket_names: