Improve email results for sharing

[nickvergessen]

Steps

1. Search for Foo Bar <foo.bar@example.tld> in the share sidebar
2. See a broken entry

Before 💥 invalid remote share	After ✨ working email share
< in user id is invalid > in server part is invalid	✅

[nickvergessen]

/backport to stable25

[nickvergessen]

/backport to stable24

[blizzz]

There was 1 failure:

1) Test\User\DatabaseTest::testSearch

/drone/src/tests/lib/User/Backend.php:114
/drone/src/tests/lib/User/DatabaseTest.php:125

I don't think it's related (also only pgsql 13 failing), but restarting ci in case. Everything else is green.

[szaimen]

/rebase