It is possible to have two activated EVCs with the same VLAN used

[Alopalao]

Related to #479
To reproduce, run this script inside the kytos virtual environment while a RingTopo is deployed.
The script should be set to always delete and restore with random.randrange(1, 2) == 1 in their if statements.

Proccess:

The script will create 7 threads. Each thread will try to add and delete 1 VLAN/EVC ~314 times.
At the end, there should be only 7 EVCs activated but instead ~12 activated EVCs with deployed paths.
Everything else is correct. The path use different VLANs and there is not duplicated flows. No errors in the logs and no http errors while creating and deleting EVCs.

Logs:

In one example I had two EVCs with the same VLAN [[1, 1]]. These were beba5ab2936043 and 4bfcbfe3d4e147.

Logs related to the first one:

13:16:27,443 - INFO [kytos.napps.kytos/mef_eline] (AnyIO worker thread) EVC(beba5ab2936043, evc1) was deployed.
13:16:27,443 - INFO [kytos.napps.kytos/mef_eline] (AnyIO worker thread) EVC(beba5ab2936043, evc1) was deployed.

Second one (which was created before and removed):

13:15:20,031 - INFO [kytos.napps.kytos/mef_eline] (AnyIO worker thread) EVC(4bfcbfe3d4e147, evc1) was deployed.
13:15:20,095 - INFO [kytos.napps.kytos/mef_eline] (AnyIO worker thread) Removing EVC(4bfcbfe3d4e147, evc1)
13:15:20,294 - INFO [kytos.napps.kytos/mef_eline] (thread_pool_app_22) Failover path for EVC(4bfcbfe3d4e147, evc1) was deployed.
13:15:20,596 - INFO [kytos.napps.kytos/mef_eline] (AnyIO worker thread) EVC removed. EVC(4bfcbfe3d4e147, evc1)
13:15:20,622 - INFO [uvicorn.access] (MainThread) 127.0.0.1:43568 - "DELETE /api/kytos/mef_eline/v2/evc/4bfcbfe3d4e147/ HTTP/1.1" 200
13:15:20,937 - INFO [kytos.napps.kytos/mef_eline] (mef_eline) EVC found in mongodb but unloaded 4bfcbfe3d4e147
13:16:21,652 - INFO [kytos.napps.kytos/mef_eline] (mef_eline) Failover path for EVC(4bfcbfe3d4e147, evc1) was deployed.

The EVC 4bfcbfe3d4e147 was restore by execute_consistency().