gitlab: Ensure to rebuild open merge requests on push events

Since recently, merge requests are not rebuilt by Jenkins when pushing
new commits to it. This could be related to some default configuration
changes in latest release of GitLab plugin for Jenkins.

As that behavior is not enabled by default in gitlab trigger settings
explicitly enable it in jenkins jobs configuration.

jobs/swh-docs.yaml

@@ -110,6 +110,7 @@
       - gitlab:
           trigger-push: true
           trigger-merge-request: true
+          trigger-open-merge-request-push: both
           trigger-note: true
           note-regex: "@jenkins.*retry.*build"
           wip-skip: false

jobs/swh-mirror.yaml

@@ -19,6 +19,7 @@
       - gitlab:
           trigger-push: true
           trigger-merge-request: true
+          trigger-open-merge-request-push: both
           add-ci-message: true
           cancel-pending-builds-on-update: true
           # secret jenkins token is generated when executing tox

jobs/templates/swh-pipeline.yaml

@@ -22,6 +22,7 @@
       - gitlab:
           trigger-push: true
           trigger-merge-request: true
+          trigger-open-merge-request-push: both
           trigger-note: true
           note-regex: "@jenkins.*retry.*build"
           wip-skip: false

jobs/tools/dockerfiles.yaml

@@ -25,6 +25,7 @@
       - gitlab:
           trigger-push: true
           trigger-merge-request: true
+          trigger-open-merge-request-push: both
           trigger-note: true
           note-regex: "@jenkins.*retry.*build"
           wip-skip: false

jobs/tools/jenkins-jobs-builder.yaml

@@ -14,6 +14,7 @@
       - gitlab:
           trigger-push: true
           trigger-merge-request: true
+          trigger-open-merge-request-push: both
           trigger-note: true
           note-regex: "@jenkins.*retry.*build"
           wip-skip: false