Clear all active connections after PostgreSQL failover tests.

spec/components/active_record/connection_adapters/postgresql_fallback_adapter_spec.rb

@@ -36,6 +36,7 @@ describe ActiveRecord::ConnectionHandling do
 
   after do
     postgresql_fallback_handler.setup!
+    postgresql_fallback_handler.clear_connections
   end
 
   describe "#postgresql_fallback_connection" do
@@ -118,8 +119,6 @@ describe ActiveRecord::ConnectionHandling do
         expect(ActiveRecord::Base.connection_pool.connections.count).to eq(0)
         expect(postgresql_fallback_handler.master_down?).to eq(nil)
 
-        skip("Only fails on Travis")
-
         expect(ActiveRecord::Base.connection)
           .to be_an_instance_of(ActiveRecord::ConnectionAdapters::PostgreSQLAdapter)
       end