loopout, liquidity: turn vars to constants

There are some numeric constants that used to be defined as vars complicating
their usage. They were turned into constants: MinLoopOutPreimageRevealDelta,
DefaultSweepConfTarget, DefaultHtlcConfTarget, DefaultSweepConfTargetDelta.

Also make liquidity.defaultHtlcConfTarget a constant, not a var.

liquidity/liquidity.go

@@ -106,13 +106,13 @@ const (
 	// time we reach timeout. We set this to a high estimate so that we can
 	// account for worst-case fees, (1250 * 4 / 1000) = 50 sat/byte.
 	defaultLoopInSweepFee = chainfee.SatPerKWeight(1250)
-)
 
-var (
 	// defaultHtlcConfTarget is the default confirmation target we use for
 	// loop in swap htlcs, set to the same default at the client.
 	defaultHtlcConfTarget = loop.DefaultHtlcConfTarget
+)
 
+var (
 	// defaultBudget is the default autoloop budget we set. This budget will
 	// only be used for automatically dispatched swaps if autoloop is
 	// explicitly enabled, so we are happy to set a non-zero value here. The

loopout.go

@@ -38,20 +38,18 @@ const (
 	// We'll try to sweep with MuSig2 at most 10 times. If that fails we'll
 	// fail back to using standard scriptspend sweep.
 	maxMusigSweepRetries = 10
-)
 
-var (
 	// MinLoopOutPreimageRevealDelta configures the minimum number of
 	// remaining blocks before htlc expiry required to reveal preimage.
-	MinLoopOutPreimageRevealDelta int32 = 20
+	MinLoopOutPreimageRevealDelta = 20
 
 	// DefaultSweepConfTarget is the default confirmation target we'll use
 	// when sweeping on-chain HTLCs.
-	DefaultSweepConfTarget int32 = 9
+	DefaultSweepConfTarget = 9
 
 	// DefaultHtlcConfTarget is the default confirmation target we'll use
 	// for on-chain htlcs published by the swap client for Loop In.
-	DefaultHtlcConfTarget int32 = 6
+	DefaultHtlcConfTarget = 6
 
 	// DefaultSweepConfTargetDelta is the delta of blocks from a Loop Out
 	// swap's expiration height at which we begin to use the default sweep