Remove policy scripts

Rhai made a decision about a route cost one to three microseconds,
some two hundred times what the same costs in Rust. That was bearable
where a function is asked once for an UPDATE, and is not where every
route is weighed against every peer, as it is when routes are passed
on. What is wanted of a policy (mark routes by where they came from,
mark what is announced, let communities say who is told what) needs no
language; it is to be configuration, done natively.

Kept from that work: route selection goes by a LOCAL_PREF that policy
set on a route from an external peer, and the lab's configuration can
be added to by a phase.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/integration-tests/tests/dialer.rs

@@ -37,8 +37,6 @@ async fn server_dialing(listener: &TcpListener, remote_asn: u32) -> Result<TestS
             import: ImportPolicy::permissive(),
             role: None,
             require_role: false,
-            import_hook: None,
-            export_hook: None,
         }];
     })
     .await
@@ -196,8 +194,6 @@ async fn test_inbound_from_configured_address_uses_config() -> Result<()> {
             import: ImportPolicy::permissive(),
             role: None,
             require_role: false,
-            import_hook: None,
-            export_hook: None,
         }];
     })
     .await?;
@@ -249,8 +245,6 @@ async fn test_local_address_is_used_as_the_source() -> Result<()> {
             import: ImportPolicy::permissive(),
             role: None,
             require_role: false,
-            import_hook: None,
-            export_hook: None,
         }];
     })
     .await?;
@@ -271,8 +265,6 @@ async fn test_local_address_is_used_as_the_source() -> Result<()> {
             import: ImportPolicy::permissive(),
             role: None,
             require_role: false,
-            import_hook: None,
-            export_hook: None,
         }];
     })
     .await?;