Mroonga CONNECTION string functionality missing after patches "partition attributes" changes

In connection with:
https://github.com/MariaDB/server/commit/bf031ec218c16e119c1d79a264deaf77a677b989

--source include/have_innodb.inc

INSTALL SONAME 'ha_mroonga';

CREATE TABLE t1 (id INT PRIMARY KEY) ENGINE=Mroonga CONNECTION='engine "InnoDB"';

START TRANSACTION;

INSERT INTO t1 VALUES (1);

ROLLBACK;

SELECT COUNT(*) FROM t1;

Prior to the patches being tested in MDEV-37833 would result in:

SELECT COUNT(*) FROM t1;

COUNT(*)

0

As the InnoDB engine setting in the Mroonga's CONNECTION string is honored and thus Mroonga becomes transactional/ACID-compliant. After the patches this option can no longer be used:

mysqltest: At line 3: query 'CREATE TABLE t1 (id INT) ENGINE=Mroonga CONNECTION='engine "InnoDB"'' failed: ER_UNKNOWN_OPTION (1911): Unknown option 'CONNECTION'

And, removing the SQL from the testcase thus results in:

SELECT COUNT(*) FROM t1;

COUNT(*)

1

As the ROLLBACK failed:

ROLLBACK;

Warnings:

Warning	1196	Some non-transactional changed tables couldn't be rolled back

It is thus important to leave the CONNECTION string in Mroonga, as it could disable actual functionality that customers/users may be using/relying on. It is also just one example; there are likely others. This testcase can be used as starter testcase for the use of CONNECTION in Mroonga.