test(TestCase): restore unregistered services correctly

Signed-off-by: Josh <josh.t.richards@gmail.com>

Author: joshtrichards

tests/lib/TestCase.php

@@ -94,7 +94,9 @@ public function restoreService(string $name): bool {
 					return $oldService;
 				});
 			} else {
-				unset($container[$oldService]);
+				// The service was not registered before the test override.
+				// Remove the test registration so the container returns to its prior state.
+				unset($container[$name]);
 			}