Update test class names to adhere to PHP style

Author: jradcliff

google-analytics-data/test/analyticsDataTest.php

@@ -22,7 +22,7 @@
 use PHPUnit\Framework\TestCase;
 use Google\Analytics\Data\V1beta\Client\BetaAnalyticsDataClient;
 
-class analyticsDataTest extends TestCase
+class AnalyticsDataTest extends TestCase
 {
     use TestTrait;
 

google-analytics-data/test/quickstartTest.php

@@ -18,7 +18,7 @@
 use Google\Cloud\TestUtils\TestTrait;
 use PHPUnit\Framework\TestCase;
 
-class quickstartTest extends TestCase
+class QuickstartTest extends TestCase
 {
     use TestTrait;