[backport#11676] contrib/init: Update openrc-run filename

Summary:
2f041f0e7 contrib/init: Update openrc-run filename (Luke Dashjr)

Pull request description:

OpenRC changed their program binary names in 2014 (3 years ago), and using the old names has loud warnings now

Backport of Core PR11676

Test Plan: I don't run any boxes that don't use systemd, can't test this

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8169