XMoveFunds: never disable_node our own node on a NODE-level failure

In a circular rebalance the destination is ourselves, so a NODE-level onion
failure (failcode & 0x2000) at the closing hop is attributed to erring_node ==
self. accumulate_failure_feedback's node-level branch called disable_node(
erring_node) unconditionally, so it disabled OUR OWN node in the persistent
clboss-xrebalance layer. askrene then treats every one of our channels as a
disabled source -- getroutes fails with 205 "source has disabled N of N
channels, leaving capacity only 0msat" -- and because disabled_nodes never
ages, every subsequent rebalance is locked out permanently (fee budget is
irrelevant). Observed on prod1: one end-of-route node failure took out all 73
source channels at once.

Guard the node-level branch: if erring_node == self_id, return without
disabling. Mirrors the self-loop guard FundsMover already has on the clboss
layer. A node-level failure blamed on us (we are the paying destination, so we
would accept) is a mis-attribution anyway and nothing about our own node should
be disabled.

Recovery for an already-poisoned layer (no askrene un-disable-node exists):
askrene-remove-layer clboss-xrebalance ; askrene-create-layer clboss-xrebalance true

Logging/behavior otherwise unchanged.

Boss/Mod/XMoveFunds/Main.cpp

@@ -1233,8 +1233,18 @@ private:
 			}
 
 			if (fail & 0x2000) {
-				/* NODE-level failure: take the whole
-				 * forwarder out of consideration. */
+				/* NODE-level failure: take the whole forwarder
+				 * out of consideration -- but NEVER our own node.
+				 * In a circular rebalance the destination is us,
+				 * so a node-level failure at the closing hop is
+				 * attributed to self; disable_node(self) would
+				 * disable ALL our channels as the source (askrene:
+				 * "source has disabled N of N channels, capacity
+				 * 0msat") and lock out every future rebalance --
+				 * permanently, since disabled_nodes does not age.
+				 * Mirrors FundsMover's self_id guard. */
+				if (std::string(enode) == std::string(self_id))
+					return;
 				actions.push_back(
 				    Boss::Mod::AskreneLayer::disable_node(
 					*rpc,