Exclude internal.fetch actors from search results
With the introduction of authorized fetch mode into Pleroma and Mastodon, every instance now has an actor used for fetching posts. Pleroma's look like internal.fetch@blob.cat (URI: https://blob.cat/internal.fetch) and Mastodon's look like niu.moe@niu.moe (URI: https://niu.moe/actor or https://niu.moe/about/more?instance_actor=true).
Both of these are useless to regular users and should not be shown in search results.