[client,management] Skip route firewall rule computation when no firewall (#7624)

* [client,management] Skip route firewall rule computation when no firewall

A peer that runs with the firewall disabled has no ACL manager and no
firewall to program, so nothing ever reads RoutesFirewallRules: the only
consumers are acl.Manager, which is reached solely when e.acl is set, and
the legacy-management probe in updateNetworkMap, which is guarded by a
non-nil firewall.

Building those rules is the most expensive part of a sync on a peer that
routes many network resources. On a 15k-peer deployment a debug bundle
showed getPeerNetworkResourceFirewallRules accounting for 62% of the
allocations of Calculate, and Calculate for effectively all of the
allocations of handleSync, which was taking 3.2s on average and holding
the engine lock for the duration.

Let the caller ask Calculate to leave the rules out. The client passes
its existing DisableFirewall setting; the management server keeps the
default and still produces them.

RoutesFirewallRulesIsEmpty is set from the resulting empty list, so a
receiver that would otherwise infer legacy management from an empty rule
set does not misread the skip.

* [client,management] Cover the skip flag through the envelope

Review feedback on #7624.

The components test compared only the length of the peer firewall rules, so
a change to their content would have passed while the message claimed they
came out unchanged. Compare the slices.

The skip path was also only exercised by setting the field directly on the
components, which bypasses the envelope conversion where
RoutesFirewallRulesIsEmpty is derived. That bit is what keeps the client from
reading skipped rules as a legacy management server, so it gets a test that
goes through EnvelopeToNetworkMap with the flag set.

* [management] Give the router a peer ACL so the rule comparison bites

Review feedback on #7624.

peer-router-1 appears in no peer ACL in the shared fixture, so its
FirewallRules came out empty and the equality assertion compared two empty
slices — it would have passed even if the peer rules were dropped entirely.

Add a policy covering the router and require the baseline to be non-empty
before comparing.

client/internal/engine.go

@@ -1061,7 +1061,11 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 			// back to empty if the FQDN doesn't have the expected shape.
 			dnsName = extractDNSDomainFromFQDN(pc.GetFqdn())
 		}
-		result, err := nbnetworkmap.EnvelopeToNetworkMap(e.ctx, envelope, localKey, dnsName)
+		// With the firewall disabled there is no ACL manager to program, so
+		// RoutesFirewallRules would be built and then dropped. On a peer that
+		// routes many network resources that is the single most expensive
+		// step of the sync.
+		result, err := nbnetworkmap.EnvelopeToNetworkMap(e.ctx, envelope, localKey, dnsName, e.config.DisableFirewall)
 		if err != nil {
 			return fmt.Errorf("decode network map envelope: %w", err)
 		}