[php8-compact] Fix Session Test errors in php8

[seamuslee001]

Overview

This fixes the following test errors on php8

• CRM_Core_SessionTest::testSetStatusWithTitleOnly
  Undefined array key "infoMessage"
• CRM_Core_SessionTest::testSetStatusWithBoth
  Undefined array key "infoType"
• CRM_Core_SessionTest::testSetStatusWithTextOnly
  Undefined array key "infoType"

Before

CRM_Core_SessionTest fails on php8

After

CRM_Core_SessionTest passes on php8

ping @eileenmcnaughton @totten @colemanw @demeritcowboy

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).