[stable18] fix display of remote users in incoming share notifications

[backportbot-nextcloud]

⚠️ This backport had conflicts and is incomplete ⚠️ adjusted manually

backport of #22062

[ChristophWurst]

@blizzz @nickvergessen I took your changes from #22062 and #22131, removed the CS clutter and combined everything into one commit with only the necessary changes. The code is quite a bit different on stable18 and thus some of the changes didn't apply. Please have a look if all the important pieces are actually there 🙏

[faily-bot]

🤖 beep boop beep 🤖

Here are the logs for the failed build:

Status of 34331: failure

mariadb10.1-php7.2

Show full log

There were 2 warnings:

1) Test\Files\ViewTest::testRenameFailDeleteTargetKeepSource
Trying to configure method "writeStream" which cannot be configured because it does not exist, has not been specified, is final, or is static

2) Test\Files\ViewTest::testCopyFailDeleteTargetKeepSource
Trying to configure method "writeStream" which cannot be configured because it does not exist, has not been specified, is final, or is static

--

There was 1 failure:

1) Test\Files\ObjectStore\ObjectStoreStorageTest::testCopyOverwrite with data set #0 ('/source.txt', '/target.txt')
Expected /target.txt to be a copy of /drone/src/tests/data/lorem.txt
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.\n
-Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.\n
-Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.\n
-Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.'
+''

/drone/src/tests/lib/Files/Storage/Storage.php:207
/drone/src/tests/lib/Files/Storage/Storage.php:248

[nickvergessen]

🐘 looks okay, but didnt execute