Update user preference Web IDE terminology

What does this MR do and why?

A tiny MR for Update user preference to reflect Beta terminology (#385922 - closed) to update the copy of the Web IDE toggle.

Old:

• Use legacy Web IDE
  _The legacy Web IDE remains available while the new Web IDE is in Beta._

New:

• Use the Web IDE Beta
  Try out the latest features in the Web IDE

Screenshots or screen recordings

N/A

How to set up and validate locally

N/A

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #385922 (closed)