Updated to latest protobuf version 21.9, proceeding as follow:

1. Download libprotobuf from
https://github.com/protocolbuffers/protobuf/releases/download/v21.9/protobuf-all-21.9.zip

2. Goto protobuf-all-21.9/python

3. python setup.py build

4. Copy `python` folder from protobuf-all-21.9 to
   the local path for `prebuilts/libprotobuf/linux`

5. Copy `src` folder from protobuf-all-21.9 to
   the local path for `prebuilts/libprotobuf/linux`,
   this is necessary for unit tests.

6. Copy `LICENSE`, `CHANGES.txt` from protobuf-all-21.9 to
   the local path for `prebuilts/libprotobuf/linux`

6. Download the prebuilt protoc compiler from
   https://github.com/protocolbuffers/protobuf/releases/download/v21.9/protoc-21.9-linux-x86_64.zip

7. Copy `bin` folder, `include` folder, `readme.txt`
   from protoc-21.9-linux-x86_64 into
   the local path for `prebuilts/libprotobuf/linux`

8. Update `METADATA` file

Bug: None
Change-Id: I8bfee218492ca001e951cb4adcc8929d14259767
(cherry picked from commit fbc6810e)