CI: Add variable containing the port for ssh access of the gitlab instance

Our server installation uses port 4444 for ssh access. The lava tests
didn't took this into account.

manifest-build.yml

@@ -6,7 +6,8 @@ variables:
   LICENSESPATH: "tmp/deploy/licenses"
   SDKPATH: "tmp/deploy/sdk/"
   DEPLOYPATH_TEST: "/artifacts/${CI_JOB_ID}/"
-  GIT_BASE_URL: "git@${CI_SERVER_HOST}:${CI_PROJECT_ROOT_NAMESPACE}"
+  GITLAB_SERVER: "${CI_SERVER_HOST}:${CI_SERVER_SSH_PORT}"
+  GIT_BASE_URL: "ssh://git@${GITLAB_SERVER}/${CI_PROJECT_ROOT_NAMESPACE}"
   TESTS_GIT_URL: "${GIT_BASE_URL}/yocto/tests.git"
 
 .docker_check: &docker_check