Fix salt.getFirstMinion() method

Partial backport of the patch:
https://gerrit.mcp.mirantis.net/#/c/25373/

Closes-Bug: https://mirantis.jira.com/browse/PROD-23521

Change-Id: Ic517ccde245272133dea48f718e74ddb2a346f6c
diff --git a/src/com/mirantis/mk/Salt.groovy b/src/com/mirantis/mk/Salt.groovy
index 6530062..8d81554 100644
--- a/src/com/mirantis/mk/Salt.groovy
+++ b/src/com/mirantis/mk/Salt.groovy
@@ -559,7 +559,7 @@
  */
 def getFirstMinion(saltId, target) {
     def minionsSorted = getMinionsSorted(saltId, target)
-    return minionsSorted[0].split("\\.")[0]
+    return minionsSorted[0]
 }
 
 /**