Revert "Upgrade grpc and abseil for SPM and cocoapods (#9486)" (#9520)

This reverts commit 9d51e8a.

Author: wu-hui

FirebaseFirestore.podspec

@@ -88,7 +88,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
 
   s.dependency 'FirebaseCore', '~> 8.0'
 
-  abseil_version = '~> 1.20211102.0'
+  abseil_version = '0.20200225.0'
   s.dependency 'abseil/algorithm', abseil_version
   s.dependency 'abseil/base', abseil_version
   s.dependency 'abseil/container/flat_hash_map', abseil_version
@@ -98,7 +98,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
   s.dependency 'abseil/time', abseil_version
   s.dependency 'abseil/types', abseil_version
 
-  s.dependency 'gRPC-C++', '~> 1.44.0'
+  s.dependency 'gRPC-C++', '~> 1.28.0'
   s.dependency 'leveldb-library', '~> 1.22'
   s.dependency 'nanopb', '~> 2.30908.0'
 

Package.swift

@@ -178,12 +178,12 @@ let package = Package(
     .package(
       name: "abseil",
       url: "https://github.com/firebase/abseil-cpp-SwiftPM.git",
-      "0.20220203.1" ..< "0.20220204.0"
+      "0.20200225.4" ..< "0.20200226.0"
     ),
     .package(
       name: "gRPC",
-      url: "https://github.com/grpc/grpc-ios.git",
-      "1.44.0-grpc" ..< "1.44.1-grpc"
+      url: "https://github.com/firebase/grpc-SwiftPM.git",
+      "1.28.4" ..< "1.29.0"
     ),
     .package(
       name: "OCMock",