Drop counterparty_spendable_height accessor

`counterparty_spendable_height` is not used outside of `package.rs`
so there's not much reason to have an accessor for it. Also, in the
next commit an issue with setting the correct value for revoked
counterparty HTLC outputs is fixed, and the upgrade path causes the
value to be 0 in some cases, making using the value in too many
places somewhat fraught.

Author: TheBlueMatt

lightning/src/chain/package.rs

@@ -834,17 +834,17 @@ impl PackageTemplate {
 				// Now check that we only merge packages if they are both unpinnable or both
 				// pinnable.
 				let self_pinnable = self_cluster == AggregationCluster::Pinnable ||
-					self.counterparty_spendable_height() <= cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
+					self.counterparty_spendable_height <= cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
 				let other_pinnable = other_cluster == AggregationCluster::Pinnable ||
-					other.counterparty_spendable_height() <= cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
+					other.counterparty_spendable_height <= cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
 				if self_pinnable && other_pinnable {
 					return true;
 				}
 
 				let self_unpinnable = self_cluster == AggregationCluster::Unpinnable &&
-					self.counterparty_spendable_height() > cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
+					self.counterparty_spendable_height > cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
 				let other_unpinnable = other_cluster == AggregationCluster::Unpinnable &&
-					other.counterparty_spendable_height() > cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
+					other.counterparty_spendable_height > cur_height + COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE;
 				if self_unpinnable && other_unpinnable {
 					return true;
 				}
@@ -855,13 +855,6 @@ impl PackageTemplate {
 	pub(crate) fn is_malleable(&self) -> bool {
 		matches!(self.malleability, PackageMalleability::Malleable(..))
 	}
-	/// The height at which our counterparty may be able to spend this output.
-	///
-	/// This is an important limit for aggregation as after this height our counterparty may be
-	/// able to pin transactions spending this output in the mempool.
-	pub(crate) fn counterparty_spendable_height(&self) -> u32 {
-		self.counterparty_spendable_height
-	}
 	pub(crate) fn previous_feerate(&self) -> u64 {
 		self.feerate_previous
 	}