Update flaky observability panels tests

[ritvibhatt]

Description

Fixes flaky adding visualization and deleting panels tests in panels 2.9

Running:  plugins/observability-dashboards/4_panels.spec.js                               (5 of 9)


  Creating visualizations
    ✓ Create first visualization in event analytics (22594ms)

  Testing panels table
    ✓ Creates a panel and redirects to the panel (8889ms)
    ✓ Duplicates a panel
    ✓ Deletes panels (9102ms)

  Testing a panel
    ✓ Move to test panel
    ✓ Change date filter of the panel

  Clean up all test data
    ✓ Deletes test panel


  7 passing (55s)


  (Results)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Tests:        7                                                                                │
  │ Passing:      7                                                                                │
  │ Failing:      0                                                                                │
  │ Pending:      0                                                                                │
  │ Skipped:      0                                                                                │
  │ Screenshots:  0                                                                                │
  │ Video:        true                                                                             │
  │ Duration:     54 seconds                                                                       │
  │ Spec Ran:     plugins/observability-dashboards/4_panels.spec.js                                │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘

Issues Resolved

[List any issues this PR will resolve]

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