All: Change references to teztnets service and mondaynet

Context

On 8th Jan 2024 we will be announcing a domain change to the Test Networks. teztnets.xyz will be deprecated and replaced with teztnets.com by 1st Feb 2024. This patch changes the URL in the various places in tests and docs across Octez.

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR