Incorrect highlight range for cross-repo hover message

Created by: olafurpg

Followup to https://github.com/sourcegraph/sourcegraph/issues/21057 and https://github.com/sourcegraph/sourcegraph/pull/21357

Steps to reproduce:

Hover on a range where

• the call-site has LSIF, but no hover message for externally imported symbols
• the definition-site has LSIF, including hover messages for exported symbols (which are imported from call-site)

Expected behavior:

The token enclosing the hover position should be highlighted.

Actual behavior:

The first token on line 0 is highlighted, see video