Improve Percy test coverage

Created by: gitstart-sourcegraph

Description

To improve web application visual test coverage by adding percy snapshot tests to more core functionalities.

Refs

Gitstart Task Sourcegraph Issue

Description

Pages To Cover

• Create Context page: Link
• Contexts list: Link
• Create batch change: Link

Success criteria

1. Important parts of the web application not covered with visual tests are identified.
   • 4h estimate.
   • use https://k8s.sgdev.org/ to explore pages that are not covered.
   • use this Percy report to see which pages are already covered.
2. Integration tests rendering these parts of the app are identified.
   • 4h estimate.
   • find integration tests here client/web/src/integration/**.test.ts.
   • see documentation on how to run integration tests locally here.
3. Percy screenshots are added to the integration tests identified in the previous step.
   • 2h estimate.
   • use percySnapshotWithVariants to make a Percy snapshot for a selected page in the integration test.