Milestones and versions are hidden after installation

[Cinc-th]

After installation of SimpleMultiProjectPlugin the existing milestones and versions are hidden on the admin pages. Note that the header still shows the number of defined milestones/versions in parantheses.

The default installation requires milestones and versions to be linked with a project. This may contribute to the problem.

But: when setting version_without_project = True the existing versions are still hidden.

[Cinc-th]

As soon as a project is defined the milestones and versions are shown. There is no need to associate the project with any item to see the effect.

Note that the project permission policy is not activated yet for this test.

[Cinc-th]

When adding the following to trac.ini the milestones and versions are visible even when no project is defined (empty database) yet.

[ticket-custom]
project.options = Project 1|

Note that when setting the variable to empty milestones and version disappear again.

[ticket-custom]
project.options = 

So presumably somewhere this variable is checked in the code.

[Cinc-th]

In 18019:

Project select control was missing when no projects were defined. Javascript code hid all the table rows because no proper selection (read no All selection) was available.

Closes #13967

[Cinc-th]

In 18020:

Don't use ticket-custom setting when gathering project data but use data from the database.

Refs #13967