TestDFSAdmin.testAllDatanodesReconfig assertion failing (again)

surfacing in the test run for HADOOP-18895 pr https://github.com/apache/hadoop/pull/6073

```
Expecting:
<["started at Thu Sep 14 23:14:07 GMT 2023SUCCESS: Changed property dfs.datanode.peer.stats.enabled",
" From: "false"",
" To: "true"",
" and finished at Thu Sep 14 23:14:07 GMT 2023."]>
to contain subsequence:
<["SUCCESS: Changed property dfs.datanode.peer.stats.enabled",
" From: "false"",
" To: "true""]>
```
looks like some logging race condition again as the "started at" output is on the same line as "SUCCESS". maybe something needs to add a \n after the started message, or before SUCCESS>