Hashtag shortcut from external instances include muted accounts

**Describe the bug**

As described in the title.

**To Reproduce**
Steps to reproduce the behaviour:
1. Add a shortcut for a hashtag from your instance.
2. Add a shortcut for the same hashtag but from an external instance.
3. See a post that is in both columns and mute the user.
4. Reload both columns. The post disappears on the first column but is there on the second one.

**Expected behavior**

Muted accounts should not be shown.

**Screenshots**

Shortcuts for the #argentina hashtag. One on mastodon.social (my instance) and the other on mas.to. Both show posts by the AllQuakes bot


Muting the bot


Now the posts are not there on the mastodon.social column but is still shown in the mas.to column.


Reproduce the issue with two hashtag shortcuts for the same tag, one local and one external, then mute an account whose post appears in both columns. Trace how each shortcut column filters posts and compare the local and external-instance paths. Done means muted-account posts disappear from both columns after reload.

Written by the indexing model from the issue text.