chainfee: change min conf target to be 1

This commit changes the minBlockTarget used by the WebAPIEstimator to be
1, inline with the bitcoind's accepted min conf target.

lntest/fee_service_test.go

@@ -34,6 +34,6 @@ func TestFeeService(t *testing.T) {
 	require.NoError(t, err)
 
 	require.Equal(
-		t, "{\"fee_by_block_target\":{\"2\":20000}}", string(body),
+		t, "{\"fee_by_block_target\":{\"1\":20000}}", string(body),
 	)
 }

lnwallet/chainfee/estimator.go

@@ -24,7 +24,7 @@ const (
 	// minBlockTarget is the lowest number of blocks confirmations that
 	// a WebAPIEstimator will cache fees for. Requesting an estimate for
 	// less than this will result in an error.
-	minBlockTarget uint32 = 2
+	minBlockTarget uint32 = 1
 
 	// minFeeUpdateTimeout represents the minimum interval in which a
 	// WebAPIEstimator will request fresh fees from its API.

lnwallet/chainfee/estimator_test.go

@@ -172,7 +172,7 @@ func TestWebAPIFeeEstimator(t *testing.T) {
 		est    uint32
 		err    string
 	}{
-		{"target_below_min", 1, 12345, 12345, "too low, minimum"},
+		{"target_below_min", 0, 12345, 12345, "too low, minimum"},
 		{"target_w_too-low_fee", 10, 42, feeFloor, ""},
 		{"API-omitted_target", 2, 0, 0, "web API does not include"},
 		{"valid_target", 20, 54321, 54321, ""},