Merge branch 'topic/ci/make_int_ts_manual' into 'master'

Make the integration testsuite run manually triggered in the CI

See merge request eng/libadalang/langkit-query-language!537

Author: HugoGGuerrier

.gitlab-ci.yml

@@ -87,6 +87,7 @@ integration-testsuite:
     - disk:100
   rules:
     - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
+      when: manual
       allow_failure: true
   parallel:
     matrix: