[php8-compact] Fix APIv4 Group Concat Test by setting dataType to be …

[seamuslee001]

…NULL if the first expression is a SQL Function

Overview

This fixes the following test failure on php8

api\v4\Action\SqlFunctionTest::testGroupAggregates
Failed asserting that an array contains '1, 122, 100.00'.

/home/jenkins/bknix-edge/build/build-2/web/sites/all/modules/civicrm/tests/phpunit/api/v4/Action/SqlFunctionTest.php:95
/home/jenkins/bknix-edge/extern/phpunit8/phpunit8.phar:671

Before

Test fails on php8

After

Test passes on php8

ping @colemanw

[civibot]

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[eileenmcnaughton]

@seamuslee001 this is snarled up in phpcs

[colemanw]

The code looks good to me, when you get tests passing this is good to go.