Xporter should assume the templates pre-installed as already installed on Store

Xporter isn't assuming the templates pre-installed as already installed on the store.

Check the following steps to reproduce the error:

1. Create a clean Jira instance and install the Xporter 5.8.2
2. After this, perform the migration to the Xporter 6.0.0
3. Go to the templates page and select the Store
4. Try to install the template "Issue Details Excel", for example.
5. You will notice you will have the same template installed twice.