[MR Analytics] Error message "hiding" below the fold

What does this MR do?

Fix MR Analytics no chart data info

The check performed to see if there was chart data was incorrect. This MR resolves that.

We were simply checking the .lenth of the data, but we actually needed to check the count for each individual month. It's correct that technically having total counts of 0 every month is still having data, but we want to hide the chart in those instances!

How to test:

1. Make sure you have starter plan.
2. Enable the feature: Feature.enable(:project_merge_request_analytics)
3. Navigate to the page: some project / analytics / Merge Requests
4. Select a date range with no data

Screenshots (strongly suggested)

Before	After

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related to #270104 (closed)