Navigate to instance settings from stack update button

[knolleary]

Fixes #1898

Description

The 'update' button on the instance overview page now takes you to /settings/overview - not the danger page that was removed a couple releases ago.

On the /settings/overview page I've removed the update button as that was also going to the danger page, whereas now the real button is on the same screen. (See the linked issue for what I mean...)

I tried a few variations of replacing the button with some notification that an update was available but nothing quite worked. Rather than spin my wheels on that, I've removed it entirely.

Related Issue(s)

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label