Kokoro: Disable gcp_ubuntu builds failing to update CMake

apt-key is deprecated and the instrutions at apt.kitware.com result in
certificate verification failures.

Bug: b/157730274
Change-Id: I58f49cf256fd660cc249668cdec5f8bf948e1309
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/57748
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/tests/kokoro/gcp_ubuntu/continuous.sh b/tests/kokoro/gcp_ubuntu/continuous.sh
index ad1d479..fba0628 100755
--- a/tests/kokoro/gcp_ubuntu/continuous.sh
+++ b/tests/kokoro/gcp_ubuntu/continuous.sh
@@ -1,5 +1,8 @@
 #!/bin/bash
 
+# FIXME(b/157730274): Updating CMake is broken
+exit 0
+
 cd git/SwiftShader
 
 set -e # Fail on any error.