pppoe: T3250: Not mangle values for tag nodes

[sever-sever]

Change Summary

Not mangle values for tag nodes for pppoe-server.
some logins use "-" for example foo@bar-bar.org

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://phabricator.vyos.net/T3250

Component(s) name

pppoe-server

Proposed changes

How to test

VyOS configuration

set service pppoe-server access-concentrator 'foo'
set service pppoe-server authentication local-users username f_oo_foo password 'test'
set service pppoe-server authentication local-users username tes2t@isp-example.com password 'test'
set service pppoe-server authentication local-users username tes3t@isp-example.com password 'test'
set service pppoe-server authentication local-users username test@isp-example.com password 'test'
set service pppoe-server client-ip-pool subnet '10.0.0.0/24'
set service pppoe-server gateway-address '192.0.2.1'
set service pppoe-server interface eth1

Secrets

vyos@r6-roll# cat /run/accel-pppd/pppoe.chap-secrets
# username  server  password  acceptable local IP addresses   shaper
f_oo_foo     * test             *               
tes2t@isp-example.com * test             *               
tes3t@isp-example.com * test             *               
test@isp-example.com * test             * 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[c-po]

Very good catch and solution!