Transformations: Match only the field spelled time when Time is configured

When the configured name is Time and the frame has a field named time
(or the other way round), the fallback still matched every time field.
Now it only matches the field with the other spelling, and keeps
matching any time field when no field goes by either name.

packages/grafana-data/src/transformations/matchers/nameMatcher.test.ts

@@ -484,6 +484,14 @@ it('Should only match the field named time when the frame has more time fields',
   expect(namesMatcher(frame.fields[0], frame, [frame])).toBeTruthy();
   expect(namesMatcher(frame.fields[1], frame, [frame])).toBeFalsy();
   expect(namesMatcher(frame.fields[2], frame, [frame])).toBeTruthy();
+
+  const aliasMatcher = getFieldMatcher({
+    id: FieldMatcherID.byName,
+    options: 'Time',
+  });
+  expect(aliasMatcher(frame.fields[0], frame, [frame])).toBeTruthy();
+  expect(aliasMatcher(frame.fields[1], frame, [frame])).toBeFalsy();
+  expect(aliasMatcher(frame.fields[2], frame, [frame])).toBeFalsy();
 });
 
 describe('Fields returned by query with refId', () => {