DDC-3820: [GH-1455] Update ExprTest.php

[doctrinebot]

Jira issue originally created by user @doctrinebot:

This issue is created automatically through a Github pull request on behalf of xoeoro:

Url: #1455

Message:

expr()->countDistinct allows to create COUNT(DISTINCT) expression with mulltiple fields but parser requires only one field.

\Doctrine\ORM\Query\Parser::AggregateExpression

some body, please, fix this problem

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-1455] was assigned:
#1455

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-1455] was merged:
#1455

[doctrinebot]

Issue was closed with resolution "Fixed"