Fix phpcs errors

Problem/Motivation

FILE: ...ules/message_notify/tests/src/Unit/Plugin/Notifier/EmailTest.php
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FOUND 0 ERRORS AND 4 WARNINGS AFFECTING 4 LINES
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 120 | WARNING | @expectedException tags should not be used, use
     |         | $this->setExpectedException() or
     |         | $this->expectException() instead
 121 | WARNING | @expectedExceptionMessage tags should not be used,
     |         | use $this->setExpectedException() or
     |         | $this->expectException() instead
 133 | WARNING | @expectedException tags should not be used, use
     |         | $this->setExpectedException() or
     |         | $this->expectException() instead
 134 | WARNING | @expectedExceptionMessage tags should not be used,
     |         | use $this->setExpectedException() or
     |         | $this->expectException() instead
----------------------------------------------------------------------

Time: 976ms; Memory: 8MB

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet