After further consideration, doing this in-app makes more sense. This
way, we'd never be able to update the desktop file automatically (e.g.,
to add a new MimeType), and removing the template zotero.desktop file
would break all existing installs using our symlink instructions.
In-app, we can update the existing desktop file on restart after an
upgrade, and we can remove the existing symlink.
This reverts commit 0ac57f8262.
This reverts commit 06741ceb62.
A couple people on Fedora 40 reported that the desktop file was no
longer working for them after this change, and it's not clear that
anyone was having trouble on Ubuntu before it -- someone just noted that
`desktop-file-validate` was showing some warnings.
Set MOZ_LEGACY_PROFILES environment variable to disable
dedicated-profile support, which creates dedicated profiles for
different channels (e.g., `esr`).
