GetAsync_UnicodeHostName_SuccessStatusCodeInResponse test failing in CI

[stephentoub]

The server this test is trying to reach is currently unreachable:

string server = "http://\uc2a4\ud0c0\ubc85\uc2a4\ucf54\ub9ac\uc544.com";

[davidsh]

// international version of the Starbucks website
// punycode: xn--oy2b35ckwhba574atvuzkc.com                
string server = "http://\uc2a4\ud0c0\ubc85\uc2a4\ucf54\ub9ac\uc544.com";

We'll need to find a new Unicode server on the internet or figure out another way to test this scenario.