[stable29] fix(settings): define a 'heartbeat' route, so SecurityHeaders can handle redirected root

[backportbot]

Backport of PR #45228

[kesselb]

1) Test\Route\RouterTest::testGenerateConsecutively
Unexpected info log: Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route "files.view.index" as such route does not exist. in /home/runner/work/server/server/3rdparty/symfony/routing/Generator/UrlGenerator.php:144
Stack trace:
#0 /home/runner/work/server/server/lib/private/Route/Router.php(410): Symfony\Component\Routing\Generator\UrlGenerator->generate('files.view.inde...', Array, 1)
#1 /home/runner/work/server/server/tests/lib/Route/RouterTest.php(68): OC\Route\Router->generate('files.view.inde...')
#2 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestCase.php(1608): Test\Route\RouterTest->testGenerateConsecutively()
#3 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestCase.php(1214): PHPUnit\Framework\TestCase->runTest()
#4 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestResult.php(728): PHPUnit\Framework\TestCase->runBare()
#5 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestCase.php(964): PHPUnit\Framework\TestResult->run(Object(Test\Route\RouterTest))
#6 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestSuite.php(684): PHPUnit\Framework\TestCase->run(Object(PHPUnit\Framework\TestResult))
#7 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestSuite.php(684): PHPUnit\Framework\TestSuite->run(Object(PHPUnit\Framework\TestResult))
#8 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/Framework/TestSuite.php(684): PHPUnit\Framework\TestSuite->run(Object(PHPUnit\Framework\TestResult))
#9 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/TextUI/TestRunner.php(653): PHPUnit\Framework\TestSuite->run(Object(PHPUnit\Framework\TestResult))
#10 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/TextUI/Command.php(144): PHPUnit\TextUI\TestRunner->run(Object(PHPUnit\Framework\TestSuite), Array, Array, true)
#11 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/src/TextUI/Command.php(97): PHPUnit\TextUI\Command->run(Array, true)
#12 /home/runner/work/server/server/vendor-bin/phpunit/vendor/phpunit/phpunit/phpunit(98): PHPUnit\TextUI\Command::main()
#13 /home/runner/work/server/server/lib/composer/bin/phpunit(122): include('/home/runner/wo...')
#14 {main}
/home/runner/work/server/server/tests/lib/Route/RouterTest.php:50
/home/runner/work/server/server/lib/private/Route/Router.php:412
/home/runner/work/server/server/tests/lib/Route/RouterTest.php:68

[kesselb]

Pushed 76efdb0 to fix the failing test.

The router uses include_once to load route definitions from the apps.

First include_once for apps/files/appinfo/routes.php returns the expected array.

Second include_once returns true, because the file was already included.

To workaround the tests must run in a separate process.

I have no idea why the test is not failing on master.

[kesselb]

To workaround the tests must run in a separate process.

That does not seem to work

I have no idea why the test is not failing on master.

The test is not failing on master because the app manager instance is mocked, the app path is null and the routing file not even included: #46416