refactor(map files): cleanup and small fixes

Lists does not get merged by grains.filter_by therefor to preserve
all items from less specific map files (i.e. osmap) they must be
copied to more specific map files (i.e. to osfingermap) otherwise,
only items from latest map file will be used.

docker/codenamemap.yaml

@@ -22,11 +22,3 @@ precise:
     deps:
       - linux-image-generic-lts-raring
       - linux-headers-generic-lts-raring
-
-CentOS Linux 7 (Core):
-  pkg:
-    deps:
-      - yum-plugin-versionlock
-      - python2-pip
-      # python-docker-py https://github.com/saltstack/salt/issues/58920
-      - rpmdevtools

docker/defaults.yaml

@@ -40,7 +40,7 @@ docker:
       name: docker-ce
       service:
         name: dockerd
-        env: null
+        env: ''
       suffix: tgz
       commands:
         - docker

docker/osfingermap.yaml

@@ -18,15 +18,22 @@ Amazon Linux-2:
 CentOS Linux-8:
   pkg:
     deps:
-      # selinux-policy
       - selinux-policy-minimum
       - python3-dnf-plugin-versionlock
+      - python3-pip
+      - iptables
+      - git
+      - tar
 
 CentOS Linux-7:
   pkg:
     deps:
       - selinux-policy-minimum
       - yum-plugin-versionlock
+      - python3-pip
+      - iptables
+      - git
+      - tar
 
 CentOS-6:
   pkg:

docker/osmap.yaml

@@ -7,7 +7,7 @@ FreeBSD:
     deps:
       - devel/py-pip
 
-Centos:
+CentOS:
   pkg:
     deps:
       - procps