fix: support customized defined className

[flying3615]

Fix for supporting customized className in GridFormDropDown.tsx

Issue happens in VectorPanel, it has a customized className, but GridCell default className GridPopoverEditDropDown-containerLarge was override by it, so move it to the last line in the editorParams to avoid override

SURVEY-24640

[B] CSD ref field in Vectors panel is missing scroll bar

Author Checklist

• appropriate description or links provided to provide context on the PR
• self reviewed, seems easy to understand and follow
• reasonable code test coverage
• change is documented in Storybook and/or markdown files

Reviewer Checklist

• Follows convention
• Does what the author says it will do
• Does not appear to cause side effects and breaking changes
  • if it does cause breaking changes, those are appropriately referenced

Post merge

• Post about the change in #lui-cop

Conventional Commit Cheat Sheet:
build: Changes that affect the build system or external dependencies (example scopes: gulp, broccoli, npm)
ci: Changes to our CI configuration files and scripts (example scopes: Circle, BrowserStack, SauceLabs)
docs: Documentation only changes
feat: A new feature
fix: A bug fix
perf: A code change that improves performance
refactor: A code change that neither fixes a bug nor adds a feature
test: Adding missing tests or correcting existing tests

[github-actions]

🎉 This PR is included in version 21.1.3 🎉

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• npm package (@latest dist-tag)
• GitHub release

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