gitlab-ci: Disable validate-x86_64-linux-deb9 job to reduce load

Enable artifacts on to ensure we have bindist coverage.

.gitlab-ci.yml

@@ -444,7 +444,8 @@ nightly-i386-linux-deb9:
   cache:
     key: linux-x86_64-deb9
 
-validate-x86_64-linux-deb9:
+# Disabled to reduce CI load
+.validate-x86_64-linux-deb9:
   extends: .build-x86_64-linux-deb9
   artifacts:
     when: always
@@ -468,6 +469,9 @@ validate-x86_64-linux-deb9-debug:
     BUILD_FLAVOUR: validate
     TEST_TYPE: slowtest
     TEST_ENV: "x86_64-linux-deb9-debug"
+  artifacts:
+    when: always
+    expire_in: 2 week
 
 # Disabled to alleviate CI load
 .validate-x86_64-linux-deb9-llvm:
@@ -791,7 +795,7 @@ doc-tarball:
     - x86_64-linux
   image: ghcci/x86_64-linux-deb9:0.2
   dependencies:
-    - validate-x86_64-linux-deb9
+    - validate-x86_64-linux-deb9-debug
     - validate-x86_64-windows
   variables:
     LINUX_BINDIST: "ghc-x86_64-deb9-linux.tar.xz"