Flatten counts for usage data to be only integers

What does this MR do?

flattens the usage ping data counts for the below to be in flat interger format

the version app, which has been modified to massage the data into the expected format, so this is a backfill of those changes into the gitlab app from which usage data originates.

before the structure of the data looked like this:

    user_preferences: {
      group_overview_details: 26,
      group_overview_security_dashboard: 0
    },
    operations_dashboard: {
      default_dashboard: 0,
      users_with_projects_added: 0
    },
    epics_deepest_relationship_level: nil

after this change it will be in expected format like the below:

      user_preferences_group_overview_details: 26,
      user_preferences_group_overview_security_dashboard: 0,
      operations_dashboard_default_dashboard: 0,
      operations_dashboard_users_with_projects_added: 0,
      epics_deepest_relationship_level: 0

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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

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