MemoryTracker accuracy test detected large untracked memory usage

[yibin87]

Our tcms test MemoryTrackerAccuracy runs 100 concurrency tpch-1 test, to check if RSS(Resident Set Size) > TrackedMaxMemory + 3.4G, it failed now. Confirmed that adjust 3.4G=>5G, the test can pass.
The increased untracked memory usage may have been introduced for a long time. However, our test framework accidentally treats error msg with "exceeds" keywork as context done, thus the real test only runs for about 10 minutes which is much smaller than the expected 1 hour.
Recently, we fixed the test framework issue, and exposed the untracked memory usage increase issue.

[yibin87]

/severity major