Dashboard: Fix library panels in collapsed rows not getting updated

[VictorColomb]

What is this feature?

This PR unifies the way that library panels are saved in a dashboard JSON, whether the library panel is in a collapsed row or not.

In practice, this PR modifies the way that a library panel inside a collapsed row gets saved.

{
    "gridPod": {...},
    "id": 123,
    "libraryPanel": {
        "uid": "z9imSuIVz",
        "name": "LIBRARY_PANEL_NAME"
    },
    "title": "PANEL_TITLE"
}

Why do we need this feature?

Library panels in collapsed rows are currently not being cleaned into the format just above and are therefore being saved with their model hardcoded. This means that they are not updated when the library panel has a new version (see attached issue below).

Who is this feature for?

Everyone!

Which issue(s) does this PR fix?:

Fixes #66640

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.

[VictorColomb]

Ping @juanicabanas @evictorero

[VictorColomb]

Hi @juanicabanas @evictorero (maybe @torkelo as well)!

Is there a hold up on this PR?

This is a pretty damaging bug for anyone who uses library panels and rows at the same time.
Could this therefore be backported to v10.0.0 since the release branch has already been created?

[torkelo]

yes, I think this should be backported

[evictorero]

Hi @VictorColomb! I tested and it is working as expected. I'm not sure about backporting it though, I will ask the team for another look at this change because I don't have enough context about the side effect that this change could have.

[VictorColomb]

I know it does in no way guarantee correct behavior, but to add some context, I forked main before the v10.0.x branch was created.

[grafanabot]

The backport to v9.5.x failed:

Server Error

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-66643-to-v9.5.x origin/v9.5.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x f478504bc9f8cdf84cb53f0cfd8d521b398aa7e7
# Push it to GitHub
git push --set-upstream origin backport-66643-to-v9.5.x
git switch main
# Remove the local backport branch
git branch -D backport-66643-to-v9.5.x

Then, create a pull request where the base branch is v9.5.x and the compare/head branch is backport-66643-to-v9.5.x.