Remove unused PhyloWidget JAR files from test folder

Remove the /treebase-web/src/main/webapp/test/phylowidget folder and its
unused JAR files (PhyloWidget.jar, core.jar, itext.jar, jgrapht-jdk1.5.jar,
pdf.jar). These files were vestiges from when PhyloWidget was being
integrated but are not referenced anywhere in the codebase.

Co-authored-by: rvosa <106490+rvosa@users.noreply.github.com>

Author: Copilot