Re-enable lb_tests in osp_verification

Octavia amphora DNS fix (OSPRH-29792) landed in content
18.0.20-20260507. May 12 periodic (build b23006c1) passed
with lb_tests enabled on this content - verified from
post-deploy log: osp_verification.yaml: PASS (1h 29m).

Reverts the disable from PR #6.

Assisted-By: Claude Code
Change-Id: I141de734c41b557f357f0f574139c9050ae35195
Signed-off-by: Itay Matza <imatza@redhat.com>

Author: imatza-rh

jobs_definitions/osp_verification.yaml

@@ -20,9 +20,7 @@ stages:
   - post
   - verification
   - openstack_test
-  # - lb_tests  # disabled until job is stabilized
-
-octavia_blocker_bugs_fixed: false
+  - lb_tests
 
 ocp_deployment_topology:
   network_type: OVNKubernetes