Optimize Dovecot configuration for IMAP tests

Closes GH-6531

Author: Girgias

ext/imap/tests/imap_errors_basic.phpt

@@ -26,6 +26,4 @@ List any errors
 array(%d) {
   [0]=>
   string(%d) "%s"
-  [1]=>
-  string(%d) "%s"
 }

ext/imap/tests/setup/dovecot.conf

@@ -2,15 +2,29 @@
 # Pigeonhole version 0.4.21 (92477967)
 listen = *, ::
 
-# To make authentication work
+# For SSL need to setup a certificate
+# See https://wiki.dovecot.org/SSL/DovecotConfiguration
 ssl = no
-disable_plaintext_auth = no
 
-auth_mechanisms = plain cram-md5
+# Disable plaintext to prevent a warning at each login
+disable_plaintext_auth = yes
+
+auth_mechanisms = cram-md5
 auth_username_format = %u
-auth_debug = yes
 auth_verbose = yes
-#log
+auth_debug = yes
+auth_failure_delay = 1secs
+
+# This need dovecot 2.3.12.
+# login_proxy_timeout = 500milliseconds
+# ^ This would allow to kill login processes early, but needs testing. So would use v instead
+# login_proxy_timeout = 5s
+# There is a 1 second delay between each reconnection attempt.
+# https://doc.dovecot.org/settings/core/#login-proxy-max-reconnects
+# This need dovecot 2.3.12.
+# login_proxy_max_reconnects = 3
+
+# Log config
 log_path = /var/log/dovecot.log
 # If not set, use the value from log_path
 info_log_path = /var/log/dovecot-info.log