Update sdwan.pm - Fix incorrect traffic counters calculation

[jummo]

Description

The traffic counters are reported via SNMP are in kbps and only needs to be multiple by 1000 to get the bps values.

From the Fortigate MIBI file:
The available bandwidth in kbps of bi-direction traffic detected by a health-check on a specific member link.

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Functionality enhancement or optimization (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software

How this pull request can be tested ?

Run
perl src/centreon_plugins.pl --plugin=network::fortinet::fortigate::snmp::plugin \ --mode sdwan \ --hostname firewall-cluster.example.com \ --snmp-version 3 \ --snmp-username='SNMP-User1' \ --authpassphrase='secret1' \ --authprotocol='SHA' \ --privpassphrase='secret2' \ --privprotocol='AES' \ --use-new-perfdata

Example SNMP data

.2.3.6.1.4.1.12356.101.4.9.2.1.2.7 = INTERNET
.1.3.6.1.4.1.12356.101.4.9.2.1.4.7 = 0
.1.3.6.1.4.1.12356.101.4.9.2.1.5.7 = 8.617
.1.3.6.1.4.1.12356.101.4.9.2.1.6.7 = 0.065
.1.3.6.1.4.1.12356.101.4.9.2.1.9.7 = 0.000
.1.3.6.1.4.1.12356.101.4.9.2.1.10.7 = root
.1.3.6.1.4.1.12356.101.4.9.2.1.11.7 = 27453
.1.3.6.1.4.1.12356.101.4.9.2.1.12.7 = 29552
.1.3.6.1.4.1.12356.101.4.9.2.1.13.7 = 57005
.1.3.6.1.4.1.12356.101.4.9.2.1.14.7 = wan1

Checklist

• I have followed the coding style guidelines provided by Centreon
• I have commented my code, especially hard-to-understand areas of the PR.
• I have rebased my development branch on the base branch (develop).
• I have provide data or shown output displaying the result of this code in the plugin area concerned.