Set default SALT_VERSION: 2017.7.7 for test-salt-formula-{{name}}-latest

  * This option to be passed into ./run_tests.sh syntax checkedю
  * This is WA for[1]: future solution should be re-implemented to relay on
    binary packages, even in tests.

[1] https://github.com/saltstack/salt/issues/46929
Related-Bug: PROD-22323 (PROD:22323)

Change-Id: Ibcc595e956b43481ce6897fc8c10d2b0b0f602b3
diff --git a/jenkins/client/job/salt-formulas/tests.yml b/jenkins/client/job/salt-formulas/tests.yml
index f2ef200..ca8d0a5 100644
--- a/jenkins/client/job/salt-formulas/tests.yml
+++ b/jenkins/client/job/salt-formulas/tests.yml
@@ -160,7 +160,7 @@
             param:
               SALT_VERSION:
                 type: string
-                default: ""
+                default: "2017.7.7"
                 description: "Version of salt for use in test, empty string means latest (default)"
               SALT_OPTS:
                 type: string