tests: Drop bigiso test (HMS-3710)

This test is being migrated to osbuild/images.

.gitlab-ci.yml

@@ -238,15 +238,6 @@ Base:
           - aws/centos-stream-9-aarch64
         INTERNAL_NETWORK: ["true"]
 
-regression-bigiso:
-  extends: .regression
-  rules:
-    # WHITELIST: Run only on x86_64 and rhel like systems
-    - if: $RUNNER =~ "/^.*(rhel-8.*x86_64|rhel-9.*x86_64|centos-stream-8.*x86_64|centos-stream-9.*x86_64).*$/" && $CI_PIPELINE_SOURCE != "schedule"
-    - !reference [.nightly_rules_x86_64, rules]
-  variables:
-    SCRIPT: regression-bigiso.sh
-
 regression-composer-works-behind-satellite-fallback:
   extends: .regression
   rules: