Improve $graphLookup query

As TRSS stores more and more data, we noticed MongoError: $graphLookup reached maximum memory consumption

```
MongoError: $graphLookup reached maximum memory consumption
at MessageStream.messageHandler (/home/testci/openjdk-test-tools/TestResultSummaryService/node_modules/mongodb/lib/cmap/connection.js:268:20)
at MessageStream.emit (events.js:198:13)
at processIncomingData (/home/testci/openjdk-test-tools/TestResultSummaryService/node_modules/mongodb/lib/cmap/message_stream.js:144:12)
```

According to the [doc](https://docs.huihoo.com/mongodb/3.4/reference/limits/index.html), `The $graphLookup stage must stay within the 100 megabyte memory limit`. We need to look into improve our $graphLookup query efficiency.

Start by locating the TRSS query that uses $graphLookup and review the MongoDB memory-limit documentation linked in the issue. Reproduce the failure with sufficiently large data, then evaluate query changes for lower memory use. Done means the query completes without the reported maximum-memory error.

Written by the indexing model from the issue text.