Downgrade gRPC and protobuf dependencies (#4666)

* downgrade grpc, proto

* also downgrade gax-grpc

dependencies.toml

@@ -28,11 +28,11 @@ finagle = "22.12.0"
 findbugs = "3.0.2"
 futures-completable = "0.3.5"
 futures-extra = "4.3.1"
-gax-grpc = "2.23.0"
+gax-grpc = "2.20.1"
 graphql-java = "20.0"
 graphql-kotlin = "6.3.5"
 groovy = "3.0.14"
-grpc-java = "1.52.1"
+grpc-java = "1.49.1"
 grpc-kotlin = "1.3.0"
 guava = "31.1-jre"
 hamcrest = "2.2"
@@ -80,7 +80,7 @@ opensaml = "3.4.6"
 osdetector = "1.7.2"
 proguard = "7.3.0"
 prometheus = "0.16.0"
-protobuf = "3.21.7"
+protobuf = "3.21.1"
 protobuf-gradle-plugin = "0.8.19"
 protobuf-jackson = "2.0.0"
 reactive-grpc = "1.2.3"