Bump retry time for cross-DC RPC

The secondary DC now takes longer to populate the MGW snapshot because
it needs to wait for the secondary CA to be initialized before it can
receive roots and generate xDS config.

Previously MGWs could receive empty roots before the CA was
initialized. This wasn't necessarily a problem since the cluster ID in
the trust domain isn't verified.

test/integration/connect/envoy/case-wanfed-gw/primary/verify.bats

@@ -23,7 +23,7 @@ load helpers
 }
 
 @test "primary should be able to rpc to the secondary" {
-  retry_default curl -sL -f -XPUT localhost:8500/v1/kv/foo?dc=secondary -d'{"Value":"bar"}'
+  retry_long curl -sL -f -XPUT localhost:8500/v1/kv/foo?dc=secondary -d'{"Value":"bar"}'
 }
 
 @test "wan pool should show 2 healthy nodes" {