there are no bucket stats in test with 1000 collections on build 7.0.0-3938

There are one scope and 1000 collections in this test. The test will insert 20M docs and then check bucket stats to make sure replica count matches. When the test checks bucket stats, there is no bucket stats. This issue is reproducible on build 7.0.0-3938.

http://172.23.133.13:8091/pools/default/buckets/bucket-1/stats

{"op":{"samples":{"timestamp":[]},"samplesCount":60,"isPersistent":true,"lastTStamp":0,"interval":1000},"hot_keys":[]}

Build: 7.0.0-3938

Job: http://perf.jenkins.couchbase.com/job/ares/18578/ 

Logs:

https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2020-12-11T202854-ns_1%40172.23.133.13.zip

https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2020-12-11T202854-ns_1%40172.23.133.14.zip

Note that,

1. Another test using default collection doesn't hit this issue on build 7.0.0-3938.
2. The same test doesn't hit this issue on build 7.0.0-4007. Therefore, I'm not sure if the issue is fixed or it just happens intermittently.
   http://perf.jenkins.couchbase.com/job/ares/18580/