[gnome-control-center] ci: Move ASAN to manual stage

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 054b16b681b4af13d1237ef9a76a1a685241f236
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Feb 20 12:00:37 2020 -0300

    ci: Move ASAN to manual stage
    
    ASAN hasn't been useful so far; we don't really see
    meaningful results from it, it takes a long time to
    run since it builds Settings twice, etc.
    
    Move it to manual.

 .gitlab-ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3378ebc9a..240b63a65 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -268,8 +268,8 @@ stop_review:
 
 asan:
   <<: *sanitizer
-  stage: test
-  when: on_success
+  stage: manual
+  when: manual
   variables:
     BUILD_OPTS: "-Db_sanitize=address"
     LSAN_OPTIONS: "suppressions=${CI_PROJECT_DIR}/build-aux/ci/lsan.supp"