logstorage: Use correct fd for fsync on gzip log files

[minminlittleshrimp]

No description provided.

[Copilot]

Pull Request Overview

This PR fixes a file synchronization issue in the DLT offline log storage system. The change corrects the file descriptor used for fsync operations when dealing with gzip-compressed log files.

• Replaces fsync(fileno(config->log)) with fsync(config->fd) for proper file synchronization
• Adds validation to ensure the file descriptor is valid before attempting fsync
• Improves error handling with appropriate error messages for invalid file descriptors

Comments suppressed due to low confidence (1)

src/offlinelogstorage/dlt_offline_logstorage_behavior.c:1125

• [nitpick] The error message could be more descriptive by including the actual file descriptor value to aid in debugging. Consider: "invalid file descriptor (%d) for log file sync"

                            dlt_vlog(LOG_ERR, "%s: invalid file descriptor for log file sync\n", __func__);

[minminlittleshrimp]

Kindly review @lti9hc

[minminlittleshrimp]

Correct commit msg and commit title -> no gzip related