\Drupal\Tests\Core\DefaultContent\FinderTest::testExceptionIfNoUuid() can cause random fails

Borrowed code from build tests.

In fact the dynamic file generation is problematic because it is never cleaned up. Let's just not do that.

Wow lovely, wonder if there is more places where we hard code write to a temp file. If we do need to write we should probably use https://www.php.net/manual/en/function.tmpfile.php to create a unique handle and cleanup.

For this test the fix makes sense to just do it staticly.

A quick scan of core test doesn't reveal any other places where file_put_contents is used that does not use a site scoped directory or tempnam/randomMachineName to generate an unique file name.

@bbrala great work on looking! I was thinking of doing the same - so nice to see it done.

This looks good. Committed/pushed to 11.x, and cherry-picked to 10.5.x, thanks!

catch → closed merge request !12043