Multiple console warning messages from Utils.cc printed on same line

## Environment
* OS Version: Ubuntu 20.04
* Source or binary build? source build of `sdf13` as of 7f63d022a48d3a224a3b7a777316c3822525c7b2

## Description
* Expected behavior: one console message should be printed per line
* Actual behavior: several messages from Utils.cc can be printed on a single line

For example from `UNIT_Geometry_TEST` in the following jenkins console output:

* https://build.osrfoundation.org/view/ign-garden/job/sdformat-ci-sdformat13-focal-amd64/78/consoleText

~~~
41: Error [Utils.cc:174] Empty string used when setting a required parameter. Key[uri]Error [Utils.cc:174] Empty string used when setting a required parameter. Key[uri][ OK ] DOMGeometry.ToElement (4 ms)
~~~

## Steps to reproduce

1. Search for `[Utils.cc` in https://build.osrfoundation.org/view/ign-garden/job/sdformat-ci-sdformat13-focal-amd64/78/consoleText
2.
3.

## Output

Start in Utils.cc, using the repeated [Utils.cc] messages in the linked Jenkins console output to trace how warnings are emitted. Reproduce the behavior through UNIT_Geometry_TEST and verify that each warning ends with its own line and no longer runs into the next warning or test result.

Written by the indexing model from the issue text.