Activity Stream filter for Projects is shown at the Global level when Application Links are configured

Issue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. Set up a vanilla Jira instance.
2. Set up a dashboard with an Activity Stream gadget.
   1. Click on Edit on the gadget and note that there is only one place to configure a filter because there is only one application.
3. Set up an application link to another Atlassian application (tested with both Jira to Jira and Jira to Confluence).
4. Note that the activity in the Activity Stream now contains data from the other instance as well. 
5. Click on Edit on the gadget.

Expected Results

You should be able to filter by Project for each Jira instance.

Actual Results

You can only filter by Project at a global level, not an application level.  

  See attachment screenshots of the gadget filters with and without an app link configured.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available.