automation: edit pipeline to fix blocked status

The original yocto config had a hidden default of allow_failure: true for the
manual job while the hidden default for rules is false. This causes the
stages with manual jobs to show as blocked.

Set it explicitly to true to avoid the analyze and build stages being shown as
blocked.

Fixes: 485ab1b5db
Signed-off-by: Victor Lira <victorm.lira@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

automation/gitlab-ci/build.yaml

@@ -229,6 +229,7 @@
   rules:
     - if: $CI_JOB_NAME =~ $SELECTED_JOBS_ONLY
       when: manual
+      allow_failure: true
 
 .yocto-test-arm64:
   extends: .yocto-test