CI: Readd allow_failure:true to fix not finished pipelines

According to the docs a manual job always has allow_failure set to
true, but we see a lot of jobs staying in an unfinished state since
the removal of the allow_failure: true keyword for the sdk and test
jobs. This should fix the broken behaviour.

manifest-build.yml

@@ -168,6 +168,7 @@ variables:
   stage: build
   rules:
     - when: manual
+      allow_failure: true
   variables:
     BITBAKE_TASK: "populate_sdk"
 
@@ -222,6 +223,7 @@ variables:
     - .package
   rules:
     - when: manual
+      allow_failure: true
   artifacts:
     paths:
       - release/**/**/*
@@ -240,6 +242,7 @@ variables:
   rules:
     - if: $CI_COMMIT_TAG
       when: manual
+      allow_failure: true
   timeout: 30m
 
 .uploadsdkftp: