[JENKINS-72679] Don't animate admin monitor popup on page load, properly remove interactable UI elements

[mawinter69]

PR #8941 caused a regression that the hiding animation was played on page load.
This change ensures that the hiding animation is only applied when the widget was visible before

Closes #8956

Testing done

Manually tested that the hiding animation is no longer shown on page load

Proposed changelog entries

• Don't animate admin monitor on page load. Fixes a regression from 2.445.

Proposed upgrade guidelines

N/A

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Desired reviewers

@mention

Before the changes are marked as ready-for-merge:

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[NotMyFault]

Please adjust the skip-changelogel label if the PR doesn't make it in tomorrow's release.

[daniel-beck]

The animation is now gone, but note #8941 (comment).

Time to revert #8791?

[mawinter69]

pushed a change that should avoid that there are still clickable artifacts. Basically the div is scaled to 0 when not visible

[daniel-beck]

Seems to work now in some limited testing.