File permisisons causing unit test to fail

[azrek]

The following unit test was failing in Totara due to file permissions:

1. totara_core_totara_testcase::test_file_bitmask
   admin/tool/heartbeat/index.php is not correctly bitmasked, it is using 755
   admin/tool/heartbeat/iplock.php is not correctly bitmasked, it is using 755
   admin/tool/heartbeat/croncheck.php is not correctly bitmasked, it is using 755

/var/www/clients/catalyst/totara/totara/core/tests/totara_test.php:63
/var/www/clients/catalyst/totara/lib/phpunit/classes/base_testcase.php:600
/var/www/clients/catalyst/totara/lib/phpunit/classes/advanced_testcase.php:68

To re-run:
vendor/bin/phpunit totara_core_totara_testcase totara/core/tests/totara_test.php

Fix:
chmod 644 admin/tool/heartbeat/index.php admin/tool/heartbeat/iplock.php admin/tool/heartbeat/croncheck.php