mwan: increase metrics between interfaces on mwan creation

[Tbaile]

While this is more a QoL improvement, filling a bug explains better the test cases.

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Steps to reproduce

• create a policy within mwan

Expected behavior

• interface metrics should be separated by intervals of 10, starting from 20

Actual behavior

• interface metrics are starting from 1 then increasing by 1

Components

• python3-nethsec: 0.0.61

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Expect that current implemented MWANs to be not updated, this fix will be just for the new creations.

Refs:

• https://github.com/NethServer/python3-nethsec/pull/55

[github-actions[bot]]

Testing image version: 8-23.05.3-ns.1.0.1-28-gf93490f

[cotosso]

Everything works as expected