Remove Discard Draft button from Page Editor toolbar

• Type: Task
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: Master
• Component/s: Pages > Page Editor
• Labels:
  • fc_20_06
• Epic/Theme:
  • Technical_Debt
• Git Pull Request: https://github.com/liferay-echo/liferay-portal/pull/1037, https://github.com/brianchandotcom/liferay-portal/pull/90040

As now is possible to discard a page draft from Pages Administration, we want to remove that button from Page Editor toolbar.