Remove dynamic dependency on protobuf

Cronet in AOSP already bundles everything related to Protobuf statically
from Chromium. This includes the runtime library (C++ and Java). The
generator is also used from Chromium. However, we were mistakenly
loading the runtime library of protobuf dynamically due to bug that
was hidden masked by incorrect propagation of shared_libs. Once the
other bug was fixed, this has showed up as extra memory consumption.

Bug: 424047788
Cq-Include-Trybots: luci.chrome.try:cronet-arm64-gn2bp-debug
Change-Id: I2522c8be04fd55db92ce818bbd2781e5774bfdb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6641229
Auto-Submit: Mohannad Farrag <aymanm@google.com>
Reviewed-by: Stefano Duo <stefanoduo@google.com>
Commit-Queue: Mohannad Farrag <aymanm@google.com>
Cr-Commit-Position: refs/heads/main@{#1474419}