Update V-13613 to align with similar code in SIMP

[djhaynes]

V-13613 in NGINX and V-71999 in SIMP RHEL 7 use similar code. We should update the NGINX control to align with the control in SIMP.

https://github.com/simp/inspec-profile-disa_stig-el7/blob/b4d53ae031ab98eb508c56fe1f48ce215db1ac61/controls/V-71999.rb