Fix #12338: Exclude .pom files from Insight's Ivy deps.

This PR excludes `.pom` files from `insight/ivy.xml`. The presence of those files in `insight/target/libs/runtime` caused a `java.util.zip.ZipException: error in opening zip file` during the `test-compile` build target.

To test:
- verify that `./build.py clean build test-compile` is free of the `ZipException`.
- check the 5.1 merge build logs (http://ci.openmicroscopy.org/view/5.1/job/OMERO-5.1-merge-build/) for the lack of the exception.