[core] Cover cpplint for /src/ray/object_manager (excluding plasma)

[elimelt]

Description

As part of the initiative to introduce cpplint into the pre-commit hook, we are gradually cleaning up C++ folders to ensure compliance with code style requirements. This issue focuses on cleaning up src/ray/object_manager (excluding plasma, as it's being covered through #50954).

Goal

Ensure all .h and .cc files in src/ray/raylet_client comply with cpplint rules.
Address or suppress all cpplint warnings.

Steps to Complete

• Checkout the latest main branch and install the pre-commit hook.
• Manually modify all C++ files in src/ray/raylet_client to trigger cpplint (e.g., by adding a newline).
• Run git commit to trigger cpplint and identify issues.
• Fix the reported issues or suppress them using clang-tidy if necessary.

This is a sub issue from #50583

[dentiny]

Thanks! Appreciate your help.

[elimelt]

Code changes done, just waiting for checks to pass before marking ready for review