fix deprecated function get_participants_counts and fix js error #155

Job	Run time
ci / check if job needs to run	8s
ci / prepare test matrix	14s
ci / MOODLE_405_STABLE - pgsql - php 8.3 - mod_reengagement	4m 54s
ci / MOODLE_405_STABLE - pgsql - php 8.1 - mod_reengagement	4m 45s
ci / MOODLE_405_STABLE - mariadb - php 8.1 - mod_reengagement	4m 40s
ci / MOODLE_405_STABLE - mariadb - php 8.3 - mod_reengagement	4m 43s
ci / Release to the Moodle plugin directory	0s
	19m 24s

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