Revert backend leak check (#586)

Reverting the backend leak check due to it killing healthy runners.

runner_manager/models/runner_group.py

@@ -313,16 +313,6 @@ def healthcheck(
     ):
         """Healthcheck runner group."""
         runners = self.get_runners()
-        backend_runners = self.backend.list()
-        # Check if there's a runner that is not in the database
-        if len(runners) != len(backend_runners):
-            for backend_runner in backend_runners:
-                if backend_runner not in runners:
-                    # A runner has leaked from the database/runner manager
-                    # let's save it and add it to the list of runners
-                    backend_runner.save()
-                    runners.append(backend_runner)
-
         for runner in runners:
             runner.update_from_github(github)
             if runner.time_to_live_expired(time_to_live):

tests/unit/jobs/test_healthchecks.py

@@ -2,6 +2,7 @@
 
 from hypothesis import given, settings
 from hypothesis import strategies as st
+from pytest import mark
 from redis_om import Migrator
 from rq import Queue
 
@@ -136,6 +137,7 @@ def test_healthcheck_job(
     assert len(runner_group.get_runners()) == 1
 
 
+@mark.skip(reason="The check was reverted due to killing healthy runners")
 def test_healthcheck_backend_leak(
     runner_group: RunnerGroup,
     settings: Settings,