nodepool: infra-package-needs; drop curl

c.f. I9ccebe2dbf3a8682dab60c2070c5f78849e01446

The RedHat platforms vary if they come pre-installed with curl or
curl-minimal, and if curl-minimal is installed, it causes conflicts
when you try to install "curl" (without removing it first, or using
"swap").

pkg-map is not designed to deal with this at all; it can't say "curl |
curl-minimal".  But all our base images come with curl, because we're
using cache-url which uses it.

So, in short, drop it here to avoid this conflict.

Change-Id: I4e930080f89fe833702f7cafef09642e0638960f

nodepool/elements/infra-package-needs/package-installs.yaml

@@ -31,6 +31,5 @@ haveged:
 iptables:
 redhat-rpm-config:
 redhat-lsb-core:
-curl:
 tox:
 gnupg2:

nodepool/elements/infra-package-needs/pkg-map

@@ -67,7 +67,6 @@
       "acl": "sys-apps/acl",
       "build-essential": "",
       "cron": "sys-process/cronie",
-      "curl": "net-misc/curl",
       "dnsutils": "net-dns/bind-tools",
       "gentoolkit": "app-portage/gentoolkit",
       "git": "dev-vcs/git",
@@ -113,7 +112,6 @@
     }
   },
   "default": {
-    "curl": "curl",
     "iptables": "iptables-persistent",
     "gentoolkit": "",
     "redhat-rpm-config": "",