chore: remove redundant backend cache invalidation

lib/logflare/backends.ex

@@ -475,7 +475,6 @@ defmodule Logflare.Backends do
   @spec clear_list_backends_cache(source_id :: integer()) :: :ok
   def clear_list_backends_cache(source_id) when is_integer(source_id) do
     Cachex.del(__MODULE__.Cache, {:list_backends, [[source_id: source_id]]})
-    Cachex.del(__MODULE__.Cache, {:list_backends, [source_id: source_id]})
     :ok
   end
 

test/logflare/backends/cache_test.exs

@@ -17,6 +17,30 @@ defmodule Logflare.Backends.CacheTest do
     {:ok, backend: backend, source: source, user: user}
   end
 
+  test "clear_list_backends_cache/1 refreshes cached source backends", %{
+    backend: backend,
+    source: source
+  } do
+    backend_id = backend.id
+
+    # Prime the cache with the backend currently associated with the source.
+    assert [%{id: ^backend_id}] = Backends.Cache.list_backends(source_id: source.id)
+
+    # Remove the association directly so the cached result remains stale.
+    assert {1, nil} =
+             Repo.delete_all(
+               from(sb in "sources_backends",
+                 where: sb.source_id == ^source.id and sb.backend_id == ^backend.id
+               )
+             )
+
+    assert [%{id: ^backend_id}] = Backends.Cache.list_backends(source_id: source.id)
+
+    # Clearing the source-specific entry makes the next lookup reflect the database.
+    assert :ok = Backends.clear_list_backends_cache(source.id)
+    assert [] = Backends.Cache.list_backends(source_id: source.id)
+  end
+
   test "warmer", %{user: user} do
     assert {:ok, []} = CacheWarmer.execute(nil)