Fix regression in abseil dependency

[abeltrano]

Type

• Bug fix
• Feature addition
• Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

• Ensure the GitHub CI/CD build succeeds.

Technical Details

The most recent version(s) of abseil, depended on by grpc and protobuf, introduced a regression where changes to its tests caused gtest became a hard dependency without adding corresponding CMake changes to locate the library.

• Fix this by adding a vcpkg overlay port for abseil, and modify the latest version to include a manually written patch that makes the erroneous test target a test-only target.

Test Results

• GitHub build validation CI/CD workflow now passes.

Reviewer Focus

• None

Future Work

• None

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.