chore: Adds RTL tests to DropdownContainer

[michael-s-molina]

SUMMARY

Adds RTL tests to DropdownContainer.

TESTING INSTRUCTIONS

1 - Execute all tests
2 - All tests should pass

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #22041 (d39461c) into master (b040211) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #22041      +/-   ##
==========================================
+ Coverage   66.96%   67.02%   +0.06%     
==========================================
  Files        1815     1815              
  Lines       69529    69551      +22     
  Branches     7480     7486       +6     
==========================================
+ Hits        46562    46619      +57     
+ Misses      21037    20996      -41     
- Partials     1930     1936       +6     

Flag	Coverage Δ
javascript	53.57% <100.00%> (+0.12%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset-frontend/src/components/Select/styles.tsx	81.81% <ø> (ø)
...rontend/src/components/DropdownContainer/index.tsx	80.00% <100.00%> (+80.00%)	⬆️
...s/superset-ui-core/src/components/SafeMarkdown.tsx	61.53% <0.00%> (-5.13%)	⬇️
...rset-frontend/src/explore/components/SaveModal.tsx	39.42% <0.00%> (-0.58%)	⬇️
...ponents/ReportModal/HeaderReportDropdown/index.tsx	67.50% <0.00%> (-0.50%)	⬇️
...perset-frontend/src/views/components/RightMenu.tsx	78.23% <0.00%> (-0.25%)	⬇️
...c/dashboard/components/gridComponents/Markdown.jsx	72.36% <0.00%> (ø)
...set-ui-core/src/ui-overrides/ExtensionsRegistry.ts	100.00% <0.00%> (ø)
...perset-frontend/src/views/CRUD/alert/AlertList.tsx	59.64% <0.00%> (+0.01%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[villebro]

This is beautiful work @michael-s-molina ! LGTM

[michael-s-molina]

This is beautiful work @michael-s-molina ! LGTM

Thank you!

[geido]

LGTM!