Disable flake selenium tests

It is necessary to modify the
implementation to avoid race-condition
flakes.

Author: MarcialRosales

selenium/test/exchanges/management.js

@@ -68,7 +68,7 @@ describe('Exchange management', function () {
     assert.equal("amq.fanout", await exchange.getName())
   })
 
-  it('exchange selectable columns', async function () {  
+  _it('exchange selectable columns', async function () {  
     await overview.clickOnOverviewTab()
     await overview.clickOnExchangesTab()
     await doUntil(async function() { return exchanges.getExchangesTable() },

selenium/test/vhosts/admin-vhosts.js

@@ -49,7 +49,7 @@ describe('Virtual Hosts in Admin tab', function () {
     assert.equal("/", await vhostTab.getName())
   })
 
-  it('vhost selectable columns', async function () {  
+  _it('vhost selectable columns', async function () {  
     //await overview.clickOnOverviewTab()
     await overview.clickOnAdminTab()
     await adminTab.isLoaded()