logs: simpler nanoscecond timestamp handling (#48773)

public/app/core/logs_model.ts

@@ -364,9 +364,7 @@ export function logSeriesToLogsModel(logSeries: DataFrame[]): LogsModel | undefi
           series,
           timeField,
           labelsField,
-          timeNanosecondField: fieldCache.hasFieldWithNameAndType('tsNs', FieldType.time)
-            ? fieldCache.getFieldByName('tsNs')
-            : undefined,
+          timeNanosecondField: fieldCache.getFieldByName('tsNs'),
           stringField,
           logLevelField: fieldCache.getFieldByName('level'),
           idField: getIdField(fieldCache),

public/app/plugins/datasource/loki/backendResultTransformer.test.ts

@@ -62,7 +62,6 @@ describe('loki backendResultTransformer', () => {
         lokiQueryStatKey: 'Summary: total bytes processed',
       },
     };
-    expectedFrame.fields[3].type = FieldType.time;
 
     const expected: DataQueryResponse = { data: [expectedFrame] };
 

public/app/plugins/datasource/loki/backendResultTransformer.ts

@@ -28,28 +28,8 @@ function processStreamFrame(frame: DataFrame, query: LokiQuery | undefined): Dat
       lokiQueryStatKey: 'Summary: total bytes processed',
     },
   };
-  const newFrame = setFrameMeta(frame, meta);
-
-  const newFields = newFrame.fields.map((field) => {
-    switch (field.name) {
-      case 'tsNs': {
-        // we need to switch the field-type to be `time`
-        return {
-          ...field,
-          type: FieldType.time,
-        };
-      }
-      default: {
-        // no modification needed
-        return field;
-      }
-    }
-  });
 
-  return {
-    ...newFrame,
-    fields: newFields,
-  };
+  return setFrameMeta(frame, meta);
 }
 
 function processStreamsFrames(frames: DataFrame[], queryMap: Map<string, LokiQuery>): DataFrame[] {