Remove similar assertions for other platforms

Testing with several platforms should not increase code coverage here,
since the DBAL is responsible for providing the concat expression for
each platform.

Moreover, whenever that concat expression changes for one of the tested
platforms, this test will break.

In doctrine/dbal 3.2, that is the case for SQLServer2012Platform, which
means this test no longer passes.

Author: greg0ire

tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php

@@ -2116,26 +2116,6 @@ public function testSupportsMoreThanTwoParametersInConcatFunction(): void
             'SELECT CONCAT(c0_.id, c0_.name, c0_.status) AS sclr_0 FROM cms_users c0_ WHERE c0_.id = ?'
         );
 
-        $connMock->setDatabasePlatform(new PostgreSQL94Platform());
-        $this->assertSqlGeneration(
-            "SELECT u.id FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE CONCAT(u.name, u.status, 's') = ?1",
-            "SELECT c0_.id AS id_0 FROM cms_users c0_ WHERE c0_.name || c0_.status || 's' = ?"
-        );
-        $this->assertSqlGeneration(
-            'SELECT CONCAT(u.id, u.name, u.status) FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE u.id = ?1',
-            'SELECT c0_.id || c0_.name || c0_.status AS sclr_0 FROM cms_users c0_ WHERE c0_.id = ?'
-        );
-
-        $connMock->setDatabasePlatform(new SQLServer2012Platform());
-        $this->assertSqlGeneration(
-            "SELECT u.id FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE CONCAT(u.name, u.status, 's') = ?1",
-            "SELECT c0_.id AS id_0 FROM cms_users c0_ WHERE (c0_.name + c0_.status + 's') = ?"
-        );
-        $this->assertSqlGeneration(
-            'SELECT CONCAT(u.id, u.name, u.status) FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE u.id = ?1',
-            'SELECT (c0_.id + c0_.name + c0_.status) AS sclr_0 FROM cms_users c0_ WHERE c0_.id = ?'
-        );
-
         $connMock->setDatabasePlatform($orgPlatform);
     }