mgd: cleanup routes from deleted bgp peer

Fixes: #349

Signed-off-by: Trey Aspelund <trey@oxidecomputer.com>

Author: taspelund

mgd/src/bgp_admin.rs

@@ -787,6 +787,17 @@ pub(crate) mod helpers {
     ) -> Result<HttpResponseDeleted, Error> {
         info!(ctx.log, "remove neighbor: {}", addr);
 
+        let id = lock!(
+            get_router!(ctx, asn)?
+                .get_session(addr)
+                .ok_or(Error::NotFound("session for bgp peer not found".into()))
+                .unwrap()
+                .session
+        )
+        .remote_id
+        .ok_or(Error::NotFound("bgp peer not found".into()))
+        .unwrap();
+        ctx.db.remove_peer_prefixes(id);
         ctx.db.remove_bgp_neighbor(addr)?;
         get_router!(&ctx, asn)?.delete_session(addr);