Events: Degrade log level to info for network related. (#698)

Why I did it
LogAnalyzer in test runs take ERR log messages as failure.
Eventd reports some network related issues as error, which could happen due to external network state.

How I did it
Reduce ERR to INFO.

How to verify it
Per issue, "config reload" triggers it,
Do config-reload and ensure no ERR message from eventd.
Issue #12303

common/events.cpp

@@ -418,7 +418,7 @@ EventSubscriber::event_receive(event_receive_op_C_t &op)
     rc = event_receive(event_str, op.missed_cnt, op.publish_epoch_ms);
     if (rc != 0) {
         if (rc != 11) {
-            SWSS_LOG_ERROR("failed to receive event. rc=%d", rc);
+            SWSS_LOG_INFO("failed to receive event. rc=%d", rc);
         }
         goto out;
     }
@@ -443,7 +443,7 @@ EventSubscriber::event_receive(event_receive_op_t &op)
     rc = event_receive(event_str, op.missed_cnt, op.publish_epoch_ms);
     if (rc != 0) {
         if (rc != 11) {
-            SWSS_LOG_ERROR("failed to receive event. rc=%d", rc);
+            SWSS_LOG_INFO("failed to receive event. rc=%d", rc);
         }
         goto out;
     }
@@ -483,7 +483,7 @@ EventSubscriber::event_receive(string &event_str, uint32_t &missed_cnt,
             rc = zmq_message_read(m_socket, 0, evt_source, event_data);
             if (rc != 0) {
                 if (rc != 11) {
-                    SWSS_LOG_ERROR("Failure to read message from sock rc=%d", rc);
+                    SWSS_LOG_INFO("Failure to read message from sock rc=%d", rc);
                 }
                 goto out;
             }

common/events_common.h

@@ -47,8 +47,8 @@ using namespace chrono;
 #define RET_ON_ERR(res, msg, ...)\
     if (!(res)) {\
         int _e = errno; \
-        SWSS_LOG_ERROR(msg, ##__VA_ARGS__); \
-        SWSS_LOG_ERROR("last:errno=%d", _e); \
+        SWSS_LOG_INFO(msg, ##__VA_ARGS__); \
+        SWSS_LOG_INFO("last:errno=%d", _e); \
         goto out; }
 
 static const int LINGER_TIMEOUT = 100;  /* Linger timeout in milliseconds */
@@ -323,7 +323,7 @@ struct serialization
             /* override with zmq err */
             rc = zmq_errno();
             if (rc != 11) {
-                SWSS_LOG_ERROR("Failure to read part rc=%d", rc);
+                SWSS_LOG_INFO("Failure to read part rc=%d", rc);
             }
         }
     out: