docs: update Aztec deprecation status to reflect shutdown

[phessophissy]

Description

This PR updates the documentation to reflect that the Aztec protocol and Aztec Connect have been fully shut down, rather than using future-tense deprecation language.

Changes

Before

"The Aztec protocol has been deprecated. Deposits and shielding are no longer accepted, and blocks will be processed until the 8th of July, 2023 to allow users to withdraw their funds."

After

"The Aztec protocol was deprecated and fully shut down on July 8th, 2023. The service is no longer operational."

Before

"This project was replaced by Aztec Connect, which in turn is being deprecated, for a new version of Aztec..."

After

"This project was replaced by Aztec Connect, which was also fully sunset, in favor of a new version of Aztec..."

Motivation

The original document was written before July 8, 2023. Since that deadline has passed, the documentation should reflect the current state rather than a future event.

Checklist

• No functional changes
• Documentation accuracy improvement
• Reflects current state of Aztec ecosystem