/usr/share/tripleo-image-elements/keystone/keystone.crontab is in python-tripleo-image-elements 0.7.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
0 */2 * * * root /usr/local/bin/cleanup-keystone-tokens.sh
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