[EuiNavDrawer] Fix scrolling in mobile view

[lokeshrana9999]

Summary

#3143
NavDrawer didn't scroll in mobile view. Problem solved using respective css selectors to modify flex-wrap property.

Checklist

• Check against all themes for compatibility in both light and dark modes
• Checked in mobile
• Checked in IE11 and Firefox
• [ ] Props have proper autodocs
• [ ] Added documentation examples
• Added or updated jest tests
• [ ] Checked for breaking changes and labeled appropriately
• [ ] Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[cchaos]

jenkins test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_3174/

[cchaos]

jenkins test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_3174/

[cchaos]

Looks like you need to update the snapshots. You'll need to run yarn run test-unit -u. I updated the checklist of in the PR summary for things that still need to be checked off.

[cchaos]

Jenkins, test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_3174/

[cchaos]

I checked in Chrome's emulator and it works now!