Description: 

Glance currently have two concurrency-related tests with overlapping scope.The first (older) tests [1] in the under of code review , and a newer tests appears to cover with all glance image operations

This story is to review both tests together, clarify their intent ,and decide whether they should be kept, merged or deprecated to avoid duplicate coverage and CI noise

Acceptance Criteria:

• Both concurrency tests reviews and compared
• Decide: keep / merge / deprecate
• Run in Upstream CI

[1]https://review.opendev.org/c/openstack/tempest/+/945320
[2] https://review.opendev.org/c/openstack/glance-tempest-plugin/+/970302