UIX will cache content even if "cached" property is disabled when "Asynchronous rendering" is enabled

When a UIX "Asynchronous rendering" property is set to true, no matter what the value of its "cached" property is, the UIX content will be cached.

Reproducible on a fresh 13.10 instance.

Step to reproduce:

• Create a new page "Sandbox.testUIX"
• add code containing user info, like:

  {{velocity}}
  crtUserDoc.fullName: $crtUserDoc.fullName
  hasAdmin: $hasAdmin
  {{/velocity}}

• set "Asynchronous rendering" to "Yes"
• set "Cached" to "No"
• set any "Extension Point ID" so that you can see the content, like "org.xwiki.platform.template.contentFooter"
• set "Extension Scope" to "Global"

To see what's going on:

• Open any page where you can see the specified extension point ("Sandbox.testUIX" should do it): it should correctly display your current user info, as it is the first time it loads.

Then:

• Open the same tab in another browser / session / firefox container, using any another user. The data shown by the UIX is still your first user info, because the result has been cached, even though the "cached" property was set to "No"