gitlab-ci: Check the Mesa version used for tracie tests

Verify that the Mesa version used when running tracie tests is the
one that was built by CI, rather than any installed distro version.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
Reviewed-by: Rohan Garg <rohan.garg@collabora.com>
Reviewed-by: Andres Gomez <agomez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3894>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c221a9c..c2b73bc 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -151,7 +151,7 @@
 x86_test-vk:
   extends: x86_build
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_test-vk "2020-04-01-jflags"
+    FDO_DISTRIBUTION_TAG: &x86_test-vk "2020-04-09"
 
 # Debian 9 based x86 build image (old LLVM)
 x86_build_old: