chore: refactor eap request transformation (#6841)

I decided that it would make sense to put request transformation step at
a different spot, not logical difference just for clarity.

snuba/web/rpc/v1/endpoint_trace_item_table.py

@@ -11,6 +11,9 @@
 from snuba.web.rpc import RPCEndpoint, TraceItemDataResolver
 from snuba.web.rpc.common.exceptions import BadSnubaRPCRequestException
 from snuba.web.rpc.v1.resolvers import ResolverTraceItemTable
+from snuba.web.rpc.v1.visitors.sparse_aggregate_attribute_transformer import (
+    SparseAggregateAttributeTransformer,
+)
 
 _GROUP_BY_DISALLOWED_COLUMNS = ["timestamp"]
 
@@ -69,6 +72,14 @@ def _validate_order_by(in_msg: TraceItemTableRequest) -> None:
         )
 
 
+def _transform_request(request: TraceItemTableRequest) -> TraceItemTableRequest:
+    """
+    This function is for initial processing and transformation of the request after recieving it.
+    It is similar to the query processor step of the snql pipeline.
+    """
+    return SparseAggregateAttributeTransformer(request).transform()
+
+
 class EndpointTraceItemTable(
     RPCEndpoint[TraceItemTableRequest, TraceItemTableResponse]
 ):
@@ -103,5 +114,8 @@ def _execute(self, in_msg: TraceItemTableRequest) -> TraceItemTableResponse:
             raise BadSnubaRPCRequestException(
                 "This endpoint requires meta.trace_item_type to be set (are you requesting spans? logs?)"
             )
+
+        in_msg = _transform_request(in_msg)
+
         resolver = self.get_resolver(in_msg.meta.trace_item_type)
         return resolver.resolve(in_msg)

snuba/web/rpc/v1/resolvers/R_eap_spans/resolver_trace_item_table.py

@@ -52,9 +52,6 @@
     get_confidence_interval_column,
     get_count_column,
 )
-from snuba.web.rpc.v1.visitors.sparse_aggregate_attribute_transformer import (
-    SparseAggregateAttributeTransformer,
-)
 
 _DEFAULT_ROW_LIMIT = 10_000
 
@@ -132,9 +129,6 @@ def _convert_order_by(
 
 
 def _build_query(request: TraceItemTableRequest) -> Query:
-    # this is similar to the query processor step of the snql pipeline
-    request = SparseAggregateAttributeTransformer(request).transform()
-
     # TODO: This is hardcoded still
     entity = Entity(
         key=EntityKey("eap_spans"),