[DataViz] Small Google Chart polish fixes

[ajpal]

• Don't show legend at all
• Add "Count" as axis label for bar charts and histogram
• Add column name as axis label for scatter plots
• Overflow auto only for cross tab charts (was causing some weird scrolling behavior for histograms)

Bar

Histogram

Scatter Plot

Cross Tab

Links

• spec
• jira
• slack thread

Testing story

Reviewer Checklist:

• Tests provide adequate coverage
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked