interfaces: regex matches VLAN bridge wrongly after migration

[Tbaile]

Steps to reproduce

• Migrate a configuration with a device section named like 'br111' (e.g. a bridge)
• Add a VLAN device that references the bridge (e.g. 'br111.112' referencing 'br111')
• Trigger device parsing logic (e.g. running ns.devices script) or browse the interfaces UI

Expected behavior

• The system should correctly distinguish between bridge and VLAN logical device names.
• VLANs referencing valid bridge names should not cause exceptions or parsing issues.

Actual behavior

• The code matches device sections named 'brNN.*' as bridges using re.match(r"^br[0-9]+(?!\.)", device.get('name', '')).
• This match is too permissive: for a config like br111.112, the VLAN device is also partially matched as a bridge, causing parsing errors.
• Ui fails to show results

Components

• ns-api: 3.4.0-r1

See also

• https://helpdesk.nethesis.it/a/tickets/195257
• https://mattermost.nethesis.it/nethesis/pl/jgadimxwcibt8dq7p9r95qg3mw