Resolve "Issue/MR list tabs - Icons sometimes display as ?"

What does this MR do?

In !44184 (merged), we replaced the badge number of MRs or Issues in the list with ? if generating the actual count was too expensive, since this was causing 500 errors. This has led to confusion, so we are going to instead remove the counts entirely if we cannot generate the true count.

To manually test this working, add count = -1 to line 220 or 221

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 #291170 (closed)