give kiwi_build more CPUs and RAM

More CPUs should speed up the builds a bit (and I *hope* the
hosts can take it, if not we can back this off). More RAM should
prevent erofs live image builds being killed due to OOM, we hope.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

templates-updates.fif.json

@@ -451,6 +451,8 @@
                 "MAX_JOB_TIME": "10800",
                 "+NUMDISKS": "3",
                 "POSTINSTALL": "_kiwi_build",
+                "QEMUCPUS": "4",
+                "QEMURAM": "8192",
                 "ROOT_PASSWORD": "weakpassword",
                 "USER_LOGIN": "false"
             }