Filter out provided dependencies when assembling p2 repo

[Calixte]

This reduces the p2 repository down to 21MB, removing all the eclipse JARs, while retaining the Maven dependencies.

% ls -1 net.sf.eclipsecs-updatesite/target/repository/plugins
io.github.classgraph.classgraph_4.8.179.jar
net.sf.eclipsecs.branding_12.0.1.202511131557.jar
net.sf.eclipsecs.checkstyle_12.0.1.202511131557.jar
net.sf.eclipsecs.core_12.0.1.202511131557.jar
net.sf.eclipsecs.core.source_12.0.1.202511131557.jar
net.sf.eclipsecs.doc_12.0.1.202511131557.jar
net.sf.eclipsecs.ui_12.0.1.202511131557.jar
net.sf.eclipsecs.ui.source_12.0.1.202511131557.jar
org.apache.commons.lang3_3.17.0.jar
org.yaml.snakeyaml_2.3.0.jar
wrapped.org.dom4j.dom4j_2.1.4.jar

[vtintillier]

Looks good to me.

@Bananeweizen given you made the repo self contained in #478, do you think it is a good idea? The idea is to reduce the size of the repository (see #914)