fix: Logger - allow variable {line} to be used without variable {file} when logging message

[michalsn]

Description
This PR fixes a bug where the {line} variable in the Logger cannot be used without specifying the {file} variable in the logged message.

Fixes #9501

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[neznaika0]

No?

Suggested change

	$this->assertGreaterThan(1, strpos($logs[0], $expected));
	$this->assertTrue(str_contains($logs[0], $expected));

[michalsn]

Yes, we can also write it this way, but I wanted to use the same style as in the previous test. This will ensure that the correct text is added to the log message. The logged message should not start with the $expected string.