Use a dialog to remove servers

[mawinter69]

requires jump to 2.568.1 to be able to load the dialog via url

• Move the Remove button from the side panel to the app bar and give it descructive color
• hide the remove button in the table when it is the last server

(built on top of #1018, also includes parts of #1019)

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[rsandell]

@mawinter69 Can you rebase this so that I can easier see the actual changes?

[mawinter69]

rebased the change. As the build now requires Java21 it fails early in the Java 17 branch. You would need to retrigger this as owner

[mawinter69]

Some tests failed due to going to 2.568.1:

• the root action is now behind a hamburger menu so we first need to click there to see the root action. Or the hamburger menu is not there at all if not visible
• build dirs with a datetime string instead of a build number are no longer supported so renamed the dirs in the zip

[mawinter69]

Disabled 2 tests in GerritServerTest that fail due to a problem with htmlunit. See the @Disabled annotation that I added

[rsandell]

It feels a bit iffy to disable tests that tests the very thing you are changing 😅