refactor(traces-qb): drop logicalForResolvedColumn

Its family branch is unreachable now that select asks metadata first. Reaching
it requires FieldFor to succeed, which requires a context on the key (getColumn
declines an unspecified one); a key carrying a context has already been put to
MatchingLogicalFields, and only lands here when that came back empty. Calling
the same function again with the same arguments therefore cannot match, and the
method reduces to the single-member field it falls back to.

Instrumenting the branch and running the traces suites confirms it: no call
reaches it with a non-empty match set.

Assisted-by: Claude Opus 5

pkg/telemetryschema/tracestelemetryschema/field_mapper.go

@@ -353,20 +353,6 @@ func (m *fieldMapper) resolveColumnExprs(
 	return exprs, existExprs, columns, nil
 }
 
-// logicalForResolvedColumn returns the logical field for a directly-resolvable key: its
-// semantic-convention family when the metadata map proves membership, otherwise the
-// single-member field for the key as given.
-func (m *fieldMapper) logicalForResolvedColumn(ctx context.Context, orgID valuer.UUID, field *telemetrytypes.TelemetryFieldKey, keys map[string][]*telemetrytypes.TelemetryFieldKey) *telemetrytypes.LogicalField {
-	for _, logical := range querybuilder.MatchingLogicalFields(ctx, orgID, m.fl, field, keys) {
-		if logical.IsFamily() &&
-			logical.FieldContext == field.FieldContext &&
-			(field.FieldDataType == telemetrytypes.FieldDataTypeUnspecified || logical.FieldDataType == field.FieldDataType) {
-			return logical
-		}
-	}
-	return telemetrytypes.SingleLogicalField(field.Name, field)
-}
-
 // upgradeToFamilies swaps single-member candidates for their family when the
 // metadata map proves membership. Candidate order and every non-family
 // candidate stay exactly as the legacy flow produced them; sibling candidates
@@ -441,7 +427,9 @@ func (m *fieldMapper) ColumnExpressionFor(
 	if len(candidates) == 0 {
 		switch _, err := m.FieldFor(ctx, orgID, startNs, endNs, field); {
 		case err == nil:
-			candidates = []*telemetrytypes.LogicalField{m.logicalForResolvedColumn(ctx, orgID, field, keys)}
+			// Metadata knows nothing about this name (it was asked above, or the key is
+			// bare and cannot resolve here at all), so the column stands alone.
+			candidates = []*telemetrytypes.LogicalField{telemetrytypes.SingleLogicalField(field.Name, field)}
 		case errors.Is(err, qbtypes.ErrColumnNotFound):
 			raw := m.CandidateKeys(ctx, orgID, field, nil, keys)
 			if len(raw) == 0 {