disabling and uninstalling projects messes up interface translation status

Noticed in #1804702-77: Display interface translation status

Problem/Motivation

Disabling project error

Disabling tamper lead to errors like

Notice: Undefined index: wysiwyg in locale_translation_status() (line 620 of core/modules/locale/locale.pages.inc).
Notice: Trying to get property of non-object in locale_translation_status() (line 620 of core/modules/locale/locale.pages.inc).

gives these 3 lines (core, tamper, wysiwyg) in the expanded details:

    Drupal core (8.x-dev). No translation files are provided for development releases.
    (no version). File not found at http://ftp.drupal.org/files/translations/8.x/locale_tamper/locale_tamper-.af.po nor at translations://locale_tamper-.af.po
    (7.x-2.1+28-dev). No translation files are provided for development releases.

The name for tamper project (and wysiwyg project which tamper provided?) are missing, but I think both of those whole lines should be gone.

uninstall projects

after uninstalling block and tamper,
in the expanded details it says:

No updates found for 2 projects

    Drupal core (8.x-dev). No translation files are provided for development releases.
    (7.x-2.1+28-dev). No translation files are provided for development releases.

[note a fix in other issue makes it say Drupal core]

Proposed resolution

Do not check and do not list projects that have been disabled or uninstalled.

Remaining tasks

• confirm problem
• wait for #1861360: Refactor localization update test so people can just enable the test module to test?

User interface changes

No UI changes.

API changes

No API changes anticipated.