locator::ec2_multi_region_snitch: don't call for ec2_snitch::gossiper_starting()

ec2_snitch::gossiper_starting() calls for the base class (default) method
that sets _gossip_started to TRUE and thereby prevents to following
reconnectable_snitch_helper registration.

Fixes #3454

Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
Message-Id: <1528208520-28046-1-git-send-email-vladz@scylladb.com>

locator/ec2_multi_region_snitch.cc

@@ -100,7 +100,6 @@ future<> ec2_multi_region_snitch::gossiper_starting() {
     // Note: currently gossiper "main" instance always runs on CPU0 therefore
     // this function will be executed on CPU0 only.
     //
-    ec2_snitch::gossiper_starting();
 
     using namespace gms;
     auto& g = get_local_gossiper();