Upgrade Abseil to LTS 20210324, Patch 2 (#27811)

* Update submodule abseil-cpp to Abseil LTS 20210324, Patch 2

* Update bazel dependencies and generate projects

* Revert podspec changes

bazel/grpc_deps.bzl

@@ -284,11 +284,11 @@ def grpc_deps():
     if "com_google_absl" not in native.existing_rules():
         http_archive(
             name = "com_google_absl",
-            sha256 = "35f22ef5cb286f09954b7cc4c85b5a3f6221c9d4df6b8c4a1e9d399555b366ee",
+            sha256 = "1764491a199eb9325b177126547f03d244f86b4ff28f16f206c7b3e7e4f777ec",
-            strip_prefix = "abseil-cpp-997aaf3a28308eba1b9156aa35ab7bca9688e9f6",
+            strip_prefix = "abseil-cpp-278e0a071885a22dcd2fd1b5576cc44757299343",
             urls = [
-                "https://storage.googleapis.com/grpc-bazel-mirror/github.com/abseil/abseil-cpp/archive/997aaf3a28308eba1b9156aa35ab7bca9688e9f6.tar.gz",
+                "https://storage.googleapis.com/grpc-bazel-mirror/github.com/abseil/abseil-cpp/archive/278e0a071885a22dcd2fd1b5576cc44757299343.tar.gz",
-                "https://github.com/abseil/abseil-cpp/archive/997aaf3a28308eba1b9156aa35ab7bca9688e9f6.tar.gz",
+                "https://github.com/abseil/abseil-cpp/archive/278e0a071885a22dcd2fd1b5576cc44757299343.tar.gz",
             ],
         )
 

third_party/abseil-cpp

@@ -1 +1 @@
-Subproject commit 997aaf3a28308eba1b9156aa35ab7bca9688e9f6
+Subproject commit 278e0a071885a22dcd2fd1b5576cc44757299343

tools/run_tests/sanity/check_submodules.sh

@@ -25,7 +25,7 @@ want_submodules=$(mktemp /tmp/submXXXXXX)
 
 git submodule | awk '{ print $2 " " $1 }' | sort >"$submodules"
 cat <<EOF | sort >"$want_submodules"
-third_party/abseil-cpp 997aaf3a28308eba1b9156aa35ab7bca9688e9f6
+third_party/abseil-cpp 278e0a071885a22dcd2fd1b5576cc44757299343
 third_party/benchmark 73d4d5e8d6d449fc8663765a42aa8aeeee844489
 third_party/bloaty 73594cde8c9a52a102c4341c244c833aa61b9c06
 third_party/boringssl-with-bazel 95b3ed1b01f2ef1d72fed290ed79fe1b0e7dafc0