e2e: Refactor the CatalogSource tests to reduce flakes (#2693)

* Refactor catalog source e2e tests to unique namespaces

Signed-off-by: perdasilva <perdasilva@redhat.com>

* e2e: Ensure the CatalogSource resource created in the global catalog test is deleted

Signed-off-by: timflannagan <timflannagan@gmail.com>

Co-authored-by: perdasilva <perdasilva@redhat.com>
Upstream-repository: operator-lifecycle-manager
Upstream-commit: 14c0b96f15368cf8f4e80a93f6b05810f9c18200

Author: timflannagan