[test] Replace assertTrue(preg_match/strpos/strstr) with assertContains
[test] Replace assertTrue(preg_match/strpos/strstr) with assertContains

Only when string offset is not relevant

netroby/zend-http,malinink/zend-http,asgrim/zend-http,weierophinney/zend-http,Maks3w/zend-http,zendframework/zend-http