Feat(eos_designs): Match using regex on platforms in platform_settings and default_interfaces

[gmuloc]

Enhancement summary

as a follow up to #4798 implementation - we should move to using regex fullmatch in the platform_settings, custom_platform_settings and default_interfaces to unify the behavior across eos_designs and gives more powerful expression to these areas.

This should be backward compatible to introduce so pretty straightforward regex

Which component of AVD is impacted

eos_designs

Use case example

easier to express.

Describe the solution you would like

cf summary

Describe alternatives you have considered

No response

Additional context

No response

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