Can't invite if profile lookup over federation is disabled

[bkil]

Describe the bug

See reproduction

Reproduction

1. Disable profile lookup over federation on the HS of the test user https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#allow_profile_lookup_over_federation
2. Open the Direct message dialog
3. Type in the full userId of the test user, click Search
4. An error will be displayed:

Searching for user... @test:example.com not found!

This error message itself should be improved, because a real error message is returned over the wire:

HTTP 403
{"errcode":"M_FORBIDDEN","error":"Profile lookup over federation is disabled on this homeserver"}

Expected behavior

You should be able to invite the test user. Tested to work correctly on Element and Hydrogen in the same scenario.

Platform and versions

-

Additional context

No response