fix: #6938 Prevent actionbar dropdown from sliding off at small widths

[jsmitrah]

Closes #6938

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

• Open the React Spectrum ActionBar component, shrink it to less than 192px, and verify the menu does not disappear.

🧢 Your Project:

[snowystinger]

Please explain the changes, because I would not have expected this property to change

[jsmitrah]

justify-content: space-between: I removed it because it wasn't doing anything.

In this grid, the third column is 1fr, which automatically takes up all the remaining space. Since there's no extra space left, justify-content: space-between has nothing to distribute. So removing it doesn't change the layout or behavior, it was simply unused code.