imapc: Change imapc_connection_retry_interval default to be 1 second.

10 secs at least is too high. Usually the connection problem is very
intermittent and even an immediate reconnection would succeed.

src/lib-storage/index/imapc/imapc-settings.c

@@ -57,7 +57,7 @@ static const struct imapc_settings imapc_default_settings = {
 	.imapc_cmd_timeout = 5*60,
 	.imapc_max_idle_time = 60*29,
 	.imapc_connection_retry_count = 1,
-	.imapc_connection_retry_interval = 10,
+	.imapc_connection_retry_interval = 1,
 	.imapc_max_line_length = 0,
 
 	.pop3_deleted_flag = ""