Mark safe usages of to_atom as such

Summary: As per title.

Differential Revision: D56935197

fbshipit-source-id: 7084b9c158b22c506925e59bec431478dcef4aa2

src/wa_raft_log_catchup.erl

@@ -144,6 +144,7 @@ is_catching_up(Catchup, Peer) ->
 %% provided RAFT partition.
 -spec default_name(Table :: wa_raft:table(), Partition :: wa_raft:partition()) -> Name :: atom().
 default_name(Table, Partition) ->
+    % elp:ignore W0023 (atoms_exhaustion) - Limit set of inputs
     list_to_atom("raft_log_catchup_" ++ atom_to_list(Table) ++ "_" ++ integer_to_list(Partition)).
 
 %% Get the registered name for the RAFT log catchup server associated with the