build-suggestions/4.7: Raise *_min to 4.y.9999

[1], child of 4.8's [2], didn't make it into 4.7.5, so we want to
block all edges into 4.7.5 (like we did for 4.7.4 in 26b44c6,
blocked-edges/4.7.4: Block all edges into 4.7.4 on vSphere node
hostnames, 2021-03-30, openshift#731).  Raising the suggestion floors into the
distant future will get 4.7.5 built without update suggestions, which
will avoid a confusing message about update sources in the generated
errata message.

[1]: https://bugzilla.redhat.com/show_bug.cgi?id=1943143
[2]: https://bugzilla.redhat.com/show_bug.cgi?id=1942207

build-suggestions/4.7.yaml

@@ -2,10 +2,10 @@
 # If you specify an arch it must have the full set of values
 ---
 default:
-  minor_min: 4.6.15
+  minor_min: 4.6.9999
   minor_max: 4.6.9999
   minor_block_list: []
-  z_min: 4.7.0
+  z_min: 4.7.9999
   z_max: 4.7.9999
   z_block_list: []
 # s390x: