fix ClientTest from cache key change

Author: bshaffer

tests/Google/ClientTest.php

@@ -714,7 +714,8 @@ public function testOnGceCacheAndCacheOptions()
         $mockCache->getItem($prefix . GCECache::GCE_CACHE_KEY)
             ->shouldBeCalledTimes(1)
             ->willReturn($mockCacheItem->reveal());
-        $mockCache->getItem(GCECredentials::cacheKey . 'universe_domain')
+        // cache key from GCECredentials::getTokenUri() . 'universe_domain'
+        $mockCache->getItem('cc685e3a0717258b6a4cefcb020e96de6bcf904e76fd9fc1647669f42deff9bf')
             ->shouldBeCalledTimes(1)
             ->willReturn($mockUniverseDomainCacheItem->reveal());