Why folder(s) in /tmp folder disappeared on CentOS?

Tmpwatch is the linux tool that recursively delete folder/files in the /tmp.

To check where is the tmpwatch related folder.
# locate tmpwatch

To configure the tmpwatch setting.
# vim /etc/cron.daily/tmpwatch

tmpwatch

tmpwatch [options] hours directory
System administration command. Recursively remove regular files and directories in directory with access times older than hours. Specify the directory as an absolute path. This command is usually invoked by cron to remove old files in the /tmp directory.

Options

-a, --all

Remove all file types.

-c, --ctime

Make decision on last inode change time for files and modification time for directories instead of access time

-d, --nodirs

Do not remove directories.

-f, --force

Force removal of read-only files (similar to rm -f).

-m, --mtime

Make decision on last modification time instead of access time.

-s, --fuser

Before deleting, attempt to use fuser to see if a file is in use.

-t, --test

Verbosely test command, but don't actually remove files.

-u, --atime

Make decision on access time. (This is the default.)

-v, --verbose

Print more details. Use two times to further increase the detail of the output.

-x, --exclude=path

Skip the specified path, the absolute path of a directory or file.