Fix auto_removal deleting wrong file during log rotation

[the-mann]

Problem

When log rotation occurs (e.g., via lumberjack), the auto_removal feature was deleting the new log file instead of the rotated one. This caused:

• Loss of fresh log data
• Repeated "no such file or directory" errors
• Gaps in log collection

Root Cause

cleanUp() used ts.tailer.Filename (a string) to remove the file. After rotation:

1. Lumberjack renames app.log → app.log.1 and creates new app.log
2. CW detects deletion, continues reading old inode via open FD
3. CW reaches EOF and calls os.Remove("app.log")
4. This deletes the new file, not the rotated one

Solution

Track the file by inode instead of filename:

• Capture inode and device number when file is opened
• At cleanup time, search for the file with that inode
• Remove the actual rotated file (e.g., app.log.1)

Testing

Added TestAutoRemovalWithLogRotation that:

• Simulates log rotation
• Verifies the rotated file is deleted
• Verifies the new file remains intact

Test passes with the fix, fails without it.

Compatibility

• Unix/Linux: Uses inode tracking
• Windows: Falls back to filename (no change in behavior)
• Existing TestLogsFileAutoRemoval still passes