Fix log level in CFStream

Downgraded some log level of some log sites  from ERROR to DEBUG.

src/core/lib/iomgr/cfstream_handle.cc

@@ -184,7 +184,7 @@ void CFStreamHandle::Ref(const char* file, int line, const char* reason) {
 void CFStreamHandle::Unref(const char* file, int line, const char* reason) {
   if (grpc_tcp_trace.enabled()) {
     gpr_atm val = gpr_atm_no_barrier_load(&refcount_.count);
-    gpr_log(GPR_ERROR,
+    gpr_log(GPR_DEBUG,
             "CFStream Handle unref %p : %s %" PRIdPTR " -> %" PRIdPTR, this,
             reason, val, val - 1);
   }

src/core/lib/iomgr/lockfree_event.cc

@@ -95,7 +95,7 @@ void LockfreeEvent::NotifyOn(grpc_closure* closure) {
      * referencing it. */
     gpr_atm curr = gpr_atm_acq_load(&state_);
     if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
-      gpr_log(GPR_ERROR, "LockfreeEvent::NotifyOn: %p curr=%p closure=%p", this,
+      gpr_log(GPR_DEBUG, "LockfreeEvent::NotifyOn: %p curr=%p closure=%p", this,
               (void*)curr, closure);
     }
     switch (curr) {
@@ -161,7 +161,7 @@ bool LockfreeEvent::SetShutdown(grpc_error* shutdown_err) {
   while (true) {
     gpr_atm curr = gpr_atm_no_barrier_load(&state_);
     if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
-      gpr_log(GPR_ERROR, "LockfreeEvent::SetShutdown: %p curr=%p err=%s",
+      gpr_log(GPR_DEBUG, "LockfreeEvent::SetShutdown: %p curr=%p err=%s",
               &state_, (void*)curr, grpc_error_string(shutdown_err));
     }
     switch (curr) {
@@ -210,7 +210,7 @@ void LockfreeEvent::SetReady() {
     gpr_atm curr = gpr_atm_no_barrier_load(&state_);
 
     if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
-      gpr_log(GPR_ERROR, "LockfreeEvent::SetReady: %p curr=%p", &state_,
+      gpr_log(GPR_DEBUG, "LockfreeEvent::SetReady: %p curr=%p", &state_,
               (void*)curr);
     }