[201911] "show sflow interface" doesn't show all interfaces enabled with sflow

[tonytitus]

Description
"show sflow interface" doesn't show all interfaces enabled with sflow

Steps to reproduce the issue:

1. config sflow interface enable all
2. show sflow interface

Describe the results you received:
If port_config.ini has 4 interfaces with same index number then only 1 interface in the list is shown.

Describe the results you expected:
All the interfaces configured with sflow should be shown

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

```
SONiC Software Version: SONiC.201911.0-74d7d3e0
Distribution: Debian 9.13
Kernel: 4.9.0-11-2-amd64
Build commit: 74d7d3e0
Build date: Tue Sep 22 23:38:49 UTC 2020
```

**Possible Fix

# git diff sonic-src/sonic-buildimage/src/sonic-utilities/show/main.p
@@ -2209,13 +2209,10 @@ def show_sflow_interface(config_db):
       click.echo("No ports configured")
       return

-    idx_to_port_map = {int(port_tbl[name]['index']): name for name in
-                       port_tbl.keys()}
   click.echo("\nsFlow interface configurations")
   header = ['Interface', 'Admin State', 'Sampling Rate']
   body = []
-    for idx in sorted(idx_to_port_map.keys()):
-        pname = idx_to_port_map[idx] 
+    for pname in natsorted(port_tbl.keys()):
       intf_key = 'SFLOW_SESSION_TABLE:' + pname
       sess_info = sess_db.get_all(sess_db.APPL_DB, intf_key)
       if sess_info is None:

[anshuv-mfst]

Dell is looking into the issue, please coordinate with @padmanarayana.

[tonytitus]

Dell is looking into the issue, please coordinate with @padmanarayana.

Raised PRS sonic-net/sonic-utilities#1141 and sonic-net/sonic-utilities#1143 with the proposed fix

[prsunny]

Merged PR - sonic-net/sonic-utilities#1143