Until the fix for JDK-8209506 [1] is available in Java 11 builds,
SSL connections to services using Google's SSL certificate do not work
due to a lack of trust. This affects both our OAuth2 client samples
which were using https://accounts.google.com as an OpenID Connect
provider.

This commit switches the two samples to use Yahoo in place of Google.

See gh-14028

[1] https://bugs.openjdk.java.net/browse/JDK-8209506