Update skip after backport (#59153)

Update a skip after backporting #59099.

Author: nik9000

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/70_adjacency_matrix.yml

@@ -67,8 +67,8 @@ setup:
 ---
 "Terms lookup":
   - skip:
-      version: " - 7.99.99"
-      reason:  fixed in 8.0.0 (backporting to 7.9.0)
+      version: " - 7.8.99"
+      reason:  fixed in 7.9.0
 
   - do:
       bulk: