/usr/lib/mysql-testsuite/std_data/loaddata4.dat is in percona-server-test-5.6 5.6.22-rel71.0-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | test row data 1 row 1 2 row 2 3 row 3
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