docs: investigate failing references

[bshaffer]

See our DocFX reference validation - we have two references failing for no clear reason:

google-cloud-php/dev/src/Command/DocFxCommand.php

Lines 45 to 50 in 9b419c4

	private static array $allowedReferenceFailures = [
	'\Google\Cloud\ResourceManager\V3\Client\ProjectsClient::testIamPermissions()'
	=> 'ProjectsClient::testIamPermissionsAsync()',
	'\Google\Cloud\Logging\V2\Client\ConfigServiceV2Client::getView()'
	=> 'ConfigServiceV2Client::getViewAsync()'
	];

These look exactly like all our other references (AFAIK), but PHPDocumentor renders their Xrefs as empty.

I believe this is an issue in phpdoc, but without further investigation, it's hard to say for sure (or even to file a useful ticket for them to fix). We should investigate this in order to fix the reference and remove the exceptions.