Revert "Only init a workspace if doesn't exists"

This reverts commit 1084cd9954.

As when we move tempest workspace to a different directory, the
directory is empty and tempest will fail to run any operation stating 
no .stestr.conf file found. In order to fix the issue, we need to do
tempest init.

Change-Id: Ia29398d3e82b880efe5e82febbc6dd6cf32b7450

tasks/tempest_post_install.yml

@@ -52,9 +52,8 @@
             if ! tempest workspace list | grep -w {{ tempest_workspace }}; then
                 tempest workspace move --name workspace --path {{ tempest_workspace }}
             fi
-        else
-           tempest init {{ tempest_workspace }}
         fi
+        tempest init {{ tempest_workspace }}
       exit 3
     fi
   args: