Pagination when total items is not in the header response

What does this MR do?

We have attempted to turn on a new implementation of issuables list in group and project, next will be epics.

We did not account for groups with over 10,000 issues, more info found here: https://docs.gitlab.com/ee/api/#other-pagination-headers

This MR accounts for this edge case and uses the compact gl-pagination when total-items is not sent from the backend.

Repro:

• Feature.enable(:vue_issuables_list)
• In Vue Dev Tools(this is the easiest way) set this.totalItems in issuables_list_app.vue to be null or undefined. Then notice that the compact gl-pagination component is rendered.

Screenshots

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