Update 2232-write-metrics-to-log entry in knownfailures.json

This test writes to LOG_STREAM(INFO) and has a check script that
verifies the output was written. This does not work on target because
LOG_STREAM is redirected to logcat. The test was already disabled due to
b/174632603, but this updates the entry's description to indicate that
this is considered by design.

Test: test/run-test --host 2232-write-metrics-to-log
Bug: 174632603
Change-Id: If2a7a5ab6529be9cefedfd3dc046191c3999115a
1 file changed