fix: Correctly delete unneeded messages on the server; Remove "Delete Messages from Server" (delete_server_after) config option (#8240)

Fix https://github.com/chatmail/core/issues/8195
Supersedes https://github.com/chatmail/core/pull/8217

The most interesting change is in `delete_expired_imap_messages()`
because there, messages are marked for deletion on single-device
chatmail profiles.

The logic in `delete_expired_imap_messages()` was wrong before, and
pre-messages were not deleted at all. This is fixed by also querying
`pre_rfc724_mid` in addition to `rfc724_mid` from the `msgs` table.
In order not to make the SQL statement too complex, I split it into two.

WRT tests:
- `test_immediate_autodelete()` tests the auto-deletion;
`test_imap_autodelete_fully_downloaded_msg()` tests that even for a
message that is split into pre- and post-message, both messages are
deleted.
- A lot of tests test that if bcc_self is on, messages are not
auto-deleted. E.g. `test_one_account_send_bcc_setting()` and
`test_markseen_message_and_mdn()` relies on the fact that messages stay
on the server when bcc_self is on.
- Unfortunately, it is not possible to test that messages are only
deleted for chatmail servers, because we don't have any tests that use a
non-chatmail server.

scripts/update-provider-database.sh

@@ -6,7 +6,7 @@ set -euo pipefail
 export TZ=UTC
 
 # Provider database revision.
-REV=ad097ee40579c884e7757de2d3bb0a51f481a32a
+REV=2cba4b72f4c6e6417b83ba549aff7781be5f166c
 
 CORE_ROOT="$PWD"
 TMP="$(mktemp -d)"