customizations: create all groups unconditionally

We had this weird condition in code that prevented composer to create groups
with the same name as a user has. This unfortunately means that you are not
able to create a user with a primary group with a certain GID that has the
same name as the user. There's the gid field in the user customization,
but it requires that the group already exists.

In order to allow that, we need to remove the condition. From now on, it's
possible to create groups with the same name as a user has, which can be used
to create primary groups with a custom gid.

Note that the lorax compatibility behaviour was actually wrong. When lorax was
given a custom gid for a user, it didn't require the gid to exist. When it
didn't, the group was just created. Thus, we still don't have full backward
compatibility, but at least we now have support for this.

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

test/data/manifests/fedora_39-x86_64-qcow2_customize-boot.json

@@ -60,6 +60,11 @@
             ],
             "uid": 1020,
             "gid": 1050
+          },
+          {
+            "name": "user3",
+            "uid": 1060,
+            "gid": 1060
           }
         ],
         "group": [
@@ -70,6 +75,10 @@
           {
             "name": "group2",
             "gid": 1050
+          },
+          {
+            "name": "user3",
+            "gid": 1060
           }
         ],
         "timezone": {
@@ -5527,6 +5536,9 @@
                 },
                 "group2": {
                   "gid": 1050
+                },
+                "user3": {
+                  "gid": 1060
                 }
               }
             }
@@ -5549,6 +5561,10 @@
                   "shell": "/bin/sh",
                   "password": "$6$BhyxFBgrEFh0VrPJ$MllG8auiU26x2pmzL4.1maHzPHrA.4gTdCvlATFp8HJU9UPee4zCS9BVl2HOzKaUYD/zEm8r/OF05F2icWB0K/",
                   "key": "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC61wMCjOSHwbVb4VfVyl5sn497qW4PsdQ7Ty7aD6wDNZ/QjjULkDV/yW5WjDlDQ7UqFH0Sr7vywjqDizUAqK7zM5FsUKsUXWHWwg/ehKg8j9xKcMv11AkFoUoujtfAujnKODkk58XSA9whPr7qcw3vPrmog680pnMSzf9LC7J6kXfs6lkoKfBh9VnlxusCrw2yg0qI1fHAZBLPx7mW6+me71QZsS6sVz8v8KXyrXsKTdnF50FjzHcK9HXDBtSJS5wA3fkcRYymJe0o6WMWNdgSRVpoSiWaHHmFgdMUJaYoCfhXzyl7LtNb3Q+Sveg+tJK7JaRXBLMUllOlJ6ll5Hod root@localhost"
+                },
+                "user3": {
+                  "uid": 1060,
+                  "gid": 1060
                 }
               }
             }