tests(refactor): mail_lmtp_ip.bats (#3004)

* chore: Drop ENV `ENABLE_POSTFIX_VIRTUAL_TRANSPORT`

* tests(chore): Remove redundant `dovecot-lmtp` config

None of this is needed. Only relevant change is changing the LMTP service listener for Dovecot and that can be delegated to `user-patches.sh`.

* tests(refactor): Use `user-patches.sh` instead of replacing config file

The only relevant changes in `test/config/dovecot-lmtp` regarding LMTP was:
- `/etc/dovecot/dovecot.conf` (`protocols = imap lmtp`) and `/etc/dovecot/protocols.d/` (`protocols = $protocols lmtp`).
- `conf.d/10-master.conf` only changed the LMTP service listener from a unix socket to TCP on port 24 (_this was the only change required for the test to pass_).

None of those configs are required as:
- `protocols = imap pop3 lmtp` [is the upstream default](https://doc.dovecot.org/settings/core/#core_setting-protocols), no need to add `lmtp`.
- The LMTP service listener is now configured for the test with `user-patches.sh`.

* tests(refactor): `mail_lmtp_ip.bats`

- Converted to new testing conventions and common container helpers.
- `ENABLE_POSTFIX_VIRTUAL_TRANSPORT` was not relevant, dropped.
- Revised test cases, logic remains the same.
- Large custom config used was not documented and doesn't appear to serve any purpose. Simplified by replacing with a single modification with `user-patches.sh`.
- Added some additional comments for context of test and improvements that could be made.

* tests(chore): Adjust comments

The comment from `mail_hostname` provides no valid context, it was likely copied over from `tests.bats` in Oct 2020 by accident.

The email sent is just for testing, nothing relevant to LMTP.

---

Added additional comment for test to reference extra information from.

* tests(chore): Update similar log line matching

Extracts out the match pattern and formatting commands into separate vars (reduces horizontal scrolling), and includes extra docs about what the matched line should be expected to look like.

docs/content/config/advanced/auth-ldap.md

@@ -189,13 +189,11 @@ The changes on the configurations necessary to work with Active Directory (**onl
 ???+ example "Basic Setup"
 
     ```yaml
-    version: '3.8'
     services:
       mailserver:
         image: docker.io/mailserver/docker-mailserver:latest
         container_name: mailserver
-        hostname: mail
-        domainname: example.com
+        hostname: mail.example.com
 
         ports:
           - "25:25"
@@ -243,7 +241,6 @@ The changes on the configurations necessary to work with Active Directory (**onl
           - SASLAUTHD_LDAP_FILTER=(&(mail=%U@example.org)(objectClass=inetOrgPerson))
           # <<< SASL LDAP Authentication
 
-          - ONE_DIR=1
           - SSL_TYPE=letsencrypt
           - PERMIT_DOCKER=host
 
@@ -254,14 +251,11 @@ The changes on the configurations necessary to work with Active Directory (**onl
 ??? example "Kopano / Zarafa"
 
     ```yaml
-    version: '3.8'
-
     services:
       mailserver:
         image: docker.io/mailserver/docker-mailserver:latest
         container_name: mailserver
-        hostname: mail
-        domainname: example.com
+        hostname: mail.example.com
 
         ports:
           - "25:25"
@@ -303,11 +297,9 @@ The changes on the configurations necessary to work with Active Directory (**onl
           # <<< Postfix Ldap Integration
 
           # >>> Kopano Integration
-          - ENABLE_POSTFIX_VIRTUAL_TRANSPORT=1
           - POSTFIX_DAGENT=lmtp:kopano:2003
           # <<< Kopano Integration
 
-          - ONE_DIR=1
           - SSL_TYPE=letsencrypt
           - PERMIT_DOCKER=host
 

docs/content/config/environment.md

@@ -197,22 +197,16 @@ Set how many days a virusmail will stay on the server before being deleted
 
 - **empty** => 7 days
 
-##### ENABLE_POSTFIX_VIRTUAL_TRANSPORT
-
-This Option is activating the Usage of POSTFIX_DAGENT to specify a ltmp client different from default dovecot socket.
-
-- **empty** => disabled
-- 1 => enabled
-
 ##### POSTFIX_DAGENT
 
-Enabled by ENABLE_POSTFIX_VIRTUAL_TRANSPORT. Specify the final delivery of postfix
+Configure Postfix `virtual_transport` to deliver mail to a different LMTP client (_default is a unix socket to dovecot_).
 
-- **empty**: fail
+Provide any valid URI. Examples:
+
+- **empty** => `lmtp:unix:/var/run/dovecot/lmtp` (default, configured in Postfix `main.cf`)
 - `lmtp:unix:private/dovecot-lmtp` (use socket)
 - `lmtps:inet:<host>:<port>` (secure lmtp with starttls)
 - `lmtp:<kopano-host>:2003` (use kopano as mailstore)
-- etc.
 
 ##### POSTFIX\_MAILBOX\_SIZE\_LIMIT