[CORE-666] - Implement liquidations healthcheck (#738)

Implement healthcheck in liquidations daemon, downgrade stale health from unhealthy to healthy + error log.

protocol/app/app.go

@@ -288,7 +288,8 @@ type App struct {
 	// can correctly operate.
 	startDaemons func()
 
-	PriceFeedClient *pricefeedclient.Client
+	PriceFeedClient    *pricefeedclient.Client
+	LiquidationsClient *liquidationclient.Client
 }
 
 // assertAppPreconditions assert invariants required for an application to start.
@@ -602,14 +603,14 @@ func New(
 			app.Server.ExpectLiquidationsDaemon(
 				daemonservertypes.MaximumAcceptableUpdateDelay(daemonFlags.Liquidation.LoopDelayMs),
 			)
+			app.LiquidationsClient = liquidationclient.NewClient(logger)
 			go func() {
-				if err := liquidationclient.Start(
+				if err := app.LiquidationsClient.Start(
 					// The client will use `context.Background` so that it can have a different context from
 					// the main application.
 					context.Background(),
 					daemonFlags,
 					appFlags,
-					logger,
 					&daemontypes.GrpcClientImpl{},
 				); err != nil {
 					panic(err)

protocol/app/app_test.go

@@ -97,11 +97,17 @@ func TestAppIsFullyInitialized(t *testing.T) {
 			tApp.InitChain()
 			uninitializedFields := getUninitializedStructFields(reflect.ValueOf(*tApp.App))
 
-			// Note that the PriceFeedClient is currently hard coded as disabled in GetDefaultTestAppOptions.
-			// Normally it would be only disabled for non-validating full nodes or for nodes where the
-			// price feed client is explicitly disabled.
-			if idx := slices.Index(uninitializedFields, "PriceFeedClient"); idx >= 0 {
-				slices.Remove(&uninitializedFields, idx)
+			// Note that the daemon clients are currently hard coded as disabled in GetDefaultTestAppOptions.
+			// Normally they would be only disabled for non-validating full nodes or for nodes where any
+			// daemon is explicitly disabled.
+			expectedUninitializedFields := []string{
+				"PriceFeedClient",
+				"LiquidationsClient",
+			}
+			for _, field := range expectedUninitializedFields {
+				if idx := slices.Index(uninitializedFields, field); idx >= 0 {
+					slices.Remove(&uninitializedFields, idx)
+				}
 			}
 
 			require.Len(