cherry-pick V2.4 (#46358)

* back fl

* delete ssl cert

* .

* make warning

* .

* unittest paral degree

* solve unittest

* heter & multi cloud commm ready

* .

* .

* fix gloo compile warning

* adapt for nn fl-ps

* flps del fake-init op

* add learning_rate_0 intializer op

* bug fix

* .

* .

python/paddle/distributed/ps/the_one_ps.py

@@ -192,6 +192,8 @@ class Accessor:
                     sgd_param.name = "SparseNaiveSGDRule"
                 if common_accessor.accessor_class == "adam":
                     sgd_param.name = "SparseAdamSGDRule"
+                else:  # for fl-ps, because geo accessor is 'sum'
+                    sgd_param.name = "SparseAdamSGDRule"
 
             if sgd_param.name == "SparseAdaGradSGDRule" or sgd_param.name == "StdAdaGradSGDRule":
                 if not sgd_param.adagrad.HasField("learning_rate"):