Merge branch 'bvl-define-version-for-migration' into 'master'

Fix the MySQL version in gitlab-ci.yml

Closes #9323

See merge request gitlab-org/gitlab-ee!9252

.gitlab-ci.yml

@@ -79,7 +79,7 @@ stages:
 
 .use-mysql: &use-mysql
   services:
-    - mysql:5.7
+    - mysql:5.7.24
     - redis:alpine
 
 # BEGIN EE-only service helpers
@@ -102,7 +102,7 @@ stages:
 
 .use-mysql-with-elasticsearch: &use-mysql-with-elasticsearch
   services:
-    - mysql:5.7
+    - mysql:5.7.24
     - redis:alpine
     - docker.elastic.co/elasticsearch/elasticsearch:5.6.12