[sheriff] Disable failing QuartcEndpointTest tests.

Disabling:

QuartcEndpointTest.ServerAcceptsOldVersion
QuartcEndpointTest.ServerNegotiatesForOldVersion

Culprit CL could not be reverted due to merge conflict, so disabling
tests instead.

TBR=vasilvv@chromium.org,rch@chromium.org
NOTRY=true

Bug: 938773
Change-Id: Id0c78e8d88519de1cfe62e2e5822e5b7db236f9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1504598Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638012}

net/third_party/quic/quartc/quartc_endpoint_test.cc

@@ -80,7 +80,7 @@ TEST_F(QuartcEndpointTest, ClientCreatesSessionAsynchronously) {
 
 // Tests that the server can negotiate for an older QUIC version if the client
 // attempts to connect using a newer version.
-TEST_F(QuartcEndpointTest, ServerNegotiatesForOldVersion) {
+TEST_F(QuartcEndpointTest, DISABLED_ServerNegotiatesForOldVersion) {
   // Note: for this test, we need support for two versions.  Which two shouldn't
   // matter, but they must be enabled so that the version manager doesn't filter
   // them out.
@@ -124,7 +124,7 @@ TEST_F(QuartcEndpointTest, ServerNegotiatesForOldVersion) {
 
 // Tests that the server can accept connections from clients that use older
 // QUIC versions.
-TEST_F(QuartcEndpointTest, ServerAcceptsOldVersion) {
+TEST_F(QuartcEndpointTest, DISABLED_ServerAcceptsOldVersion) {
   // Note: for this test, we need support for two versions.  Which two shouldn't
   // matter, but they must be enabled so that the version manager doesn't filter
   // them out.