mod_cluster balancer improperly decodes proxied requests

Issue

• We use a mod_cluster balancer to proxy requests, but it improperly decodes requests before proxying them. For instance, if we request /proxy-canon/foo%2Bbar, it is proxied to the backend as /proxy-canon/foo+bar. Or /proxy-canon/foo%2Fbar is proxied through as /proxy-canon/foo%252Fbar.