VXLAN: Fix oper_status and tunnel encapsulation TTL

This fixes 2 issues across a range of open tickets building upon patches
created by others with modifications as requested by @VladimirKuk.

The first issue this resolves is the status shown for remote vteps
which in the fact that it is wrong makes debugging nearly impossible:
```
+------------+------------+-------------------+--------------+
| SIP        | DIP        | Creation Source   | OperStatus   |
+============+============+===================+==============+
| 172.16.0.1 | 172.16.0.2 | EVPN              | oper_down    |
+------------+------------+-------------------+--------------+
Total count : 1
```

The VTEP is really up.

Original PR for that is sonic-net#2080.

Also fixes sonic-net/sonic-buildimage#10004
or at least the error message which hurts debugging.

The next issue is in reachabiity across VXLANs.  This fixes IP/MAC
learning via ARP.  The original PR for that is sonic-net#3216, however it
appears it has its origins in
sonic-net/sonic-buildimage#10050
which goes into greater detail about the issue itself.  Also there
is talk about it here kamelnetworks/sonic#9 as well as another
similar patch here: kamelnetworks@02ee3e3

Fixes sonic-net#3216
Fixes sonic-net#2080
Fixes sonic-net/sonic-buildimage#10050
Fixes sonic-net/sonic-buildimage#10004
Signed-off-by: Brad House (@bradh352)

orchagent/portsorch.cpp

@@ -6222,7 +6222,9 @@ bool PortsOrch::addTunnel(string tunnel_alias, sai_object_id_t tunnel_id, bool h
     {
         tunnel.m_learn_mode = SAI_BRIDGE_PORT_FDB_LEARNING_MODE_DISABLE;
     }
+    tunnel.m_oper_status = SAI_PORT_OPER_STATUS_DOWN;
     m_portList[tunnel_alias] = tunnel;
+    saiOidToAlias[tunnel_id] = tunnel_alias;
 
     SWSS_LOG_INFO("addTunnel:: %" PRIx64, tunnel_id);
 
@@ -6233,6 +6235,7 @@ bool PortsOrch::removeTunnel(Port tunnel)
 {
     SWSS_LOG_ENTER();
 
+    saiOidToAlias.erase(tunnel.m_tunnel_id);
     m_portList.erase(tunnel.m_alias);
 
     return true;
@@ -6972,9 +6975,10 @@ void PortsOrch::updatePortOperStatus(Port &port, sai_port_oper_status_t status)
         return;
     }
 
+    updateDbPortOperStatus(port, status);
+
     if (port.m_type == Port::PHY)
     {
-        updateDbPortOperStatus(port, status);
         updateGearboxPortOperStatus(port);
 
         /* Refresh the port states and reschedule the poller tasks */

orchagent/vxlanorch.cpp

@@ -274,7 +274,7 @@ create_tunnel(
     sai_ip_address_t *dst_ip,
     sai_object_id_t underlay_rif,
     bool p2p,
-    sai_uint8_t encap_ttl=0)
+    sai_uint8_t encap_ttl=DEFAULT_TUNNEL_ENCAP_TTL)
 {
     sai_attribute_t attr;
     std::vector<sai_attribute_t> tunnel_attrs;
@@ -348,16 +348,13 @@ create_tunnel(
         tunnel_attrs.push_back(attr);
     }
 
-    if (encap_ttl != 0)
-    {
-        attr.id = SAI_TUNNEL_ATTR_ENCAP_TTL_MODE;
-        attr.value.s32 = SAI_TUNNEL_TTL_MODE_PIPE_MODEL;
-        tunnel_attrs.push_back(attr);
+    attr.id = SAI_TUNNEL_ATTR_ENCAP_TTL_MODE;
+    attr.value.s32 = SAI_TUNNEL_TTL_MODE_PIPE_MODEL;
+    tunnel_attrs.push_back(attr);
 
-        attr.id = SAI_TUNNEL_ATTR_ENCAP_TTL_VAL;
-        attr.value.u8 = encap_ttl;
-        tunnel_attrs.push_back(attr);
-    }
+    attr.id = SAI_TUNNEL_ATTR_ENCAP_TTL_VAL;
+    attr.value.u8 = encap_ttl;
+    tunnel_attrs.push_back(attr);
 
     sai_object_id_t tunnel_id;
     sai_status_t status = sai_tunnel_api->create_tunnel(

orchagent/vxlanorch.h

@@ -46,6 +46,7 @@ typedef enum
 #define MAX_VLAN_ID 4095
 
 #define MAX_VNI_ID 16777215
+#define DEFAULT_TUNNEL_ENCAP_TTL 64
 
 typedef enum
 {