[tune] Add on_pause, on_unpause to ConcurrencyLimiter (#10320)

Co-authored-by: Richard Liaw <rliaw@berkeley.edu>

python/ray/tune/suggest/suggestion.py

@@ -304,3 +304,9 @@ class ConcurrencyLimiter(Searcher):
 
     def set_state(self, state):
         self.__dict__.update(state)
+
+    def on_pause(self, trial_id):
+        self.searcher.on_pause(trial_id)
+
+    def on_unpause(self, trial_id):
+        self.searcher.on_unpause(trial_id)