Caldav after Opt out of IMip still advertising auto-scheduling

[dugite-code]

Using Thunderbird with nextcloud caldav event invites cannot be sent even if the Send invitations to attendees option is unset.

As commented by @zyro23 on #6811 in order to allow clients to know the server won't send event invites the line $server->addPlugin(new \OCA\DAV\CalDAV\Schedule\Plugin()); in apps/dav/lib/Server.php needs to be commented out.

@georgehrke Stated that moving this line into the if ($sendInvitations) section would not be advisable as this might break free busy.

As I don't use Free/busy I have moved that line and will report any other issues I encounter with this.

[georgehrke]

Duplicate of #8423

Please comment there in the future

[dugite-code]

Opps sorry, apparently user name searches don't work so I missed that