Test CIoManagerTest/testFileIoGood is flaky on linux-x86_64.

[edsavage]

The CIoManagerTest/testFileIoGood fails intermittently (~ 1% of the time) on the linux-x86_64 CI builds. The error message is always:

Got 1 failure and 0 errors.
failure
fatal error

ASSERTION FAILURE:
- file   : CIoManagerTest.cc
- line   : 91
- message: critical check processedData.length() == threadReader.data().length() has failed [10000 != 8192]

The suspected source of the failure is in CThreadDataReader in the test library, although this has not been confirmed.