remove conformance_test targets from CI on windows. (#1170)

diff --git a/buildkite/pipelines/protobuf-postsubmit.yml b/buildkite/pipelines/protobuf-postsubmit.yml
index 657418c..6b42906 100644
--- a/buildkite/pipelines/protobuf-postsubmit.yml
+++ b/buildkite/pipelines/protobuf-postsubmit.yml
@@ -24,3 +24,5 @@
       # https://github.com/bazelbuild/bazel/issues/10590
       - "-//:cc_proto_blacklist_test"
       - "@com_google_protobuf//:cc_proto_blacklist_test"
+      - "-//java/core:conformance_test"
+      - "-//java/lite:conformance_test"