FLAKE: //test/cpp/end2end:xds_end2end_test@poller=epollex[k8-opt] UsesXdsResolver/LocalityMapTest.UpdateMap/0

https://source.cloud.google.com/results/invocations/3c353373-6396-40e1-8951-2a0487197c77/targets/%2F%2Ftest%2Fcpp%2Fend2end:xds_end2end_test@poller%3Depollex/tests

```
test/cpp/end2end/xds_end2end_test.cc:1315
Value of: locality_picked_rates[i]
Expected: (is >= 0.177778) and (is <= 0.266667)
  Actual: 0.273 (of type double)
```