Rename 'Registrar WHOIS Server' to 'WHOIS Server'

[bessone]

Hello,

in the whois output, the Port43 value is incorrectly named "Registrar Whois Server," but in the registry response, this is the registry's whois server, not the registrar's.

Here's an example:

rdap google.xyz --whois

RDAP from Registry:
Domain Name: google.xyz
Handle: D2689447-CNIC
Registrar WHOIS Server: whois.nic.xyz
Creation Date: 2014-05-20T12:04:51.0Z
Expiration Date: 2026-11-26T23:59:59.0Z
Updated Date: 2025-11-11T12:00:30.0Z
Registrar: MarkMonitor, Inc (TLDs)
Registrar IANA ID: 292
Domain Status: client transfer prohibited
Domain Status: client update prohibited
Domain Status: client delete prohibited
Name Server: ns1.google.com
Name Server: ns2.google.com
Name Server: ns3.google.com
Name Server: ns4.google.com


RDAP from Registrar:
Domain Name: google.xyz
Handle: D2689447-CNIC
Registrar WHOIS Server: whois.markmonitor.com
Expiration Date: 2026-11-26T00:00:00.000+00:00
Creation Date: 2014-05-20T12:04:51.000+00:00
Updated Date: 2025-10-25T10:10:19.000+00:00
Registrar: Markmonitor Inc.
Registrar IANA ID: 292
Domain Status: client update prohibited
Domain Status: client transfer prohibited
Domain Status: client delete prohibited
Registrant Name: REDACTED REGISTRANT
Registrant Street: REDACTED FOR PRIVACY
Registrant Locality: REDACTED FOR PRIVACY
Registrant Post Code: REDACTED FOR PRIVACY
Registrant Tel: REDACTED FOR PRIVACY
Registrant Email: REDACTED FOR PRIVACY
Name Server: ns1.google.com
Name Server: ns2.google.com
Name Server: ns3.google.com
Name Server: ns4.google.com

This PR renames the label to a generic "WHOIS Server" to resolve the issue.

[wolveix]

Sorry this sat for so long @bessone, thank you!