docs: updated equinix_metal_connection examples

[ocobles]

• some examples with ecx resource were updated with the fabric resource but without using the correct fabric fields
• renaming examples to use the same terminology as that available in the documentation https://deploy.equinix.com/developers/docs/metal/interconnections/fabric-billed-fabric-vc/ https://deploy.equinix.com/developers/docs/metal/interconnections/metal-billed-fabric-vc/
• fixed errors in examples (tested)
• removed note "Service Token A-side / Z-side (service_token_type) is not generally available" since it's been GA for more than a year
• Removed example using legacy not automated workflow since it was deprecated
• fixes [Docs]: some equinix_fabric_connection using deprecated equinix_ecx_l2_connection fields #777

[ctreatma]

Given the current codeowner mappings, this PR requires review from @equinix/governor-digin-fabric before GitHub will allow it to be merged.

If that review requirement is not acceptable/desirable, we should update the codeowner mappings in a separate PR so that docs file names for each Equinix service can reference other Equinix services without requiring review from the relevant service teams.

[srushti-patl]

LGTM

[github-actions]

This PR is included in version 2.6.0 🎉