Feature/dev 6966 tables styling

[adamdoe]

[DEV-6966] Preview Styling Updates

• Remove thead-dark class to get blue styling
• Verify teahd-dark class wasn't being used anywhere
• Make preview table 100% width
• Add slight margin above the table
• Change scroll behavior to default

Testing Steps

• Open the editor
• Import any data set
• Verify the table takes up 100% of the width it normally should
• Verify the table has the blue theme that matches visualization data tables

Self Review

• I have added testing steps for reviewers
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests are passing

Screenshots (if applicable)

Additional Notes