Remove obsolete Drupal\system\Tests\Module\InstallUninstallTest

Problem

1. Drupal\system\Tests\Module\InstallUninstallTest takes 14 minutes (23%) of the total core test suite time.

2. That is not acceptable in any way.

Proposed solution

1. Remove the test without replacement. It is obsolete.

2. Re-add missing coverage for the few discrete edge-cases to ModuleHandlerTest.

   → #2254203: Fix test performance of Drupal\system\Tests\Module\ModuleApiTest

Details

1. This test is useless, because it is a "wildcard" test — instead of testing discrete functionality/regressions, it doesn't know what to test, so it blatantly tests each and everything in the hope that it will catch "something".
2. I've studied the test code to see what expectations are actually covered. (see below)

3. The vast majority has been made obsolete by major code refactoring in Drupal 8 (cf. ModuleHandler).

   This test predates Drupal 8. It mostly tried to address the D7/D6 architecture of modules/extensions, in which

   1. The database schema had to be installed + uninstalled manually.
   2. Variables had to be created + deleted manually.
   3. Both the installation and the uninstallation process consisted of tons of spaghetti code and wasn't centralized yet.
4. Only a few edge-cases are explicitly covered, mostly pertaining to "required" modules.

Known regression test coverage

1. Assert that all "required" modules are already installed by default.
2. Assert that other modules are not installed by default.
3. Assert that installing a module with dependencies shows a confirmation screen. → duplicates DependencyTest
4. Assert that installing a module installs all of its dependencies. → duplicates DependencyTest
5. Assert that a module's database schema is installed.
6. Assert that a module's config is installed. → duplicates ConfigInstallTest and ConfigInstallWebTest
7. Assert that a message is logged for each installed module.
8. Assert that hook_modules_installed() is invoked.
9. Assert that an installed module can be uninstalled.
10. Assert that a module's database schema is uninstalled.
11. Assert that a module's config is uninstalled. → duplicates ConfigInstallTest and ConfigInstallWebTest
12. Assert that a message is logged for each uninstalled module.
13. Assert that hook_modules_uninstalled() is invoked.
14. Assert that "required" modules are not uninstalled. → duplicates ModuleApiTest
15. Assert that a module can be re-installed after uninstalling it.
16. Assert that multiple modules can be installed at the same time. → duplicates DependencyTest
17. Asserts that all modules provided by core can be installed and then modules uninstalled.