Fix Kokoro windows build script from environment change #911
Description
Script needs to point to a different location for Java 8
https://github.com/GoogleCloudPlatform/appengine-plugins-core/blob/50403ccc2c6d00de72c26b7398f89cad8d3fb530/kokoro/continuous.bat#L4
Error: JAVA_HOME is set to an invalid directory.
JAVA_HOME = "c:\program files\java\jdk1.8.0_152"
Please set the JAVA_HOME variable in your environment to match the
location of your Java installation.