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
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 1d801e9..385db45 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1358,7 +1358,6 @@
     {
         "tests": ["2232-write-metrics-to-log"],
         "variant": "target",
-        "description": ["Fails on target on go/art-buildbot."],
-        "bug": "b/174632603"
+        "description": ["Checks LOG_STREAM output, which cannot be captured on target."]
     }
 ]