maven: Remove extraction of groupId and artifactId from pom files

When parsing pom files, we are only interested to extract a VCS URL
(git, hg, svn) in order to create associated loading tasks.

In that case, the groupId and artifactId are not used by the lister
so better removing their extraction, plus it will prevent errors when
those info are missing in pom files.

swh/lister/maven/lister.py

@@ -252,14 +252,10 @@ class MavenLister(Lister[MavenListerState, RepoPage]):
                 if scm_d is not None:
                     connection = scm_d.get("connection")
                     if connection is not None:
-                        scm = connection
-                        gid = project_d["groupId"]
-                        aid = project_d["artifactId"]
                         artifact_metadata_d = {
                             "type": "scm",
                             "doc": out_pom[pom],
-                            "url": scm,
-                            "project": f"{gid}.{aid}",
+                            "url": connection,
                         }
                         logger.debug("* Yielding pom %s: %s", pom, artifact_metadata_d)
                         yield artifact_metadata_d