[ENHANCEMENT] Allow migration of empty panel dashboard

[ying-jeanne]

Description

Hi folks, I am first time contributor of this repo, not sure we are aligned the fix on this ticket #1536. This PR intent to allow migration of empty panels dashboard from Grafana, and remove the panels check in the schema of dashboard v1.

Screenshots

Checklist

• Pull request has a descriptive title and context useful to a reviewer.
• Pull request title follows the [<catalog_entry>] <commit message> naming convention using one of the
  following catalog_entry values: FEATURE, ENHANCEMENT, BUGFIX, BREAKINGCHANGE, DOC,IGNORE.
• All commits have DCO signoffs.

UI Changes

• na Changes that impact the UI include screenshots and/or screencasts of the relevant changes.
• na Code follows the UI guidelines.
• na Visual tests are stable and unlikely to be flaky.
  See Storybook
  and e2e docs for more details. Common issues
  include:
  • Is the data inconsistent? You need to mock API requests.
  • Does the time change? You need to use consistent time values or mock time utilities.
  • Does it have loading states? You need to wait for loading to complete.

[Nexucis]

I think we can merge it right @AntoineThebaud ?

Once the log is removed, should be good to merge excepting if you have other comments @AntoineThebaud

[Nexucis]

awesome thank you @ying-jeanne !