Remove text for sandbox in replCommand

[Sdywolf]

This PR modifies behaviour or interface

Fix #10482

Text provided by Setup.hs repl --help contained outdated information concerning sandbox, which have now been removed.

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
• The documentation has been updated, if necessary.
• Manual QA notes have been included.
• Tests have been added.

[geekosaur]

This is user-visible (granting, not very, but it is help text) and as such probably requires a changelog entry, although it's not major. Also it's probably worth backporting.

[ulysses4ever]

I'm not sure about the changelog but since technically it is a visible change and there's a voice for it, sure...

[ulysses4ever]

Changelogs are described here btw: https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#changelog

[geekosaur]

I'm not sure about the changelog but since technically it is a visible change and there's a voice for it, sure...

Yeh, it's borderline, but it is user-visible. Maybe someone else should speak up yea/nay.

[Sdywolf]

Thx for reminding me. I will check CONTRIBUTING.md and add changelog entry.