refactor(log): remove deprecated utility/log.h

- Remove src/libipc/utility/log.h as it's no longer used
- All code has been migrated to use the new libipc/imp/log.h interface
- The old utility/log.h provided printf-style logging: ipc::log() and ipc::error()
- The new imp/log.h provides modern C++ stream-based logging with LIBIPC_LOG() macro
- Verified that there are no remaining references to utility/log.h in the codebase

This completes the log interface migration by removing the deprecated file.

Author: mutouyun