Have you tried changing it by replacing the file for ex: "abcd.svg" present under the directory "/usr/share/kibana/optimize/bundles/".Images with png extension works as well.
Refreshing the browser alone is sufficient.
Path; /usr/share/kibana/optimize/bundles/src/ui/public/images
Apache, Apache Lucene, Apache Hadoop, Hadoop, HDFS and the yellow elephant
logo are trademarks of the
Apache Software Foundation
in the United States and/or other countries.