[core] Cover cpplint for src/ray/object_manager/plasma

[CheyuWu]

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/plasma.

Goal

• Ensure all .h and .cc files in src/ray/object_manager/plasma 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/object_manager/plasma 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!