Fix _cat/store sort test to use a reliable sort value

using the store size is not reliable since it's cached and might
be stale depending on the timing when the cache entry was generated.

rest-api-spec/src/main/resources/rest-api-spec/test/cat.shards/10_basic.yaml

@@ -256,11 +256,11 @@
 
   - do:
       cat.shards:
-        h: [index, store]
-        s: [store]
+        h: [index, docs]
+        s: [docs]
 
-  - match:
+  - match: # don't use the store here it's cached and might be stale
       $body: |
-            /^ foo \s+ (\d+|\d+[.]\d+)(kb|b)\n
-               bar \s+ (\d+|\d+[.]\d+)(kb|b)\n
+            /^ foo \s+ 0\n
+               bar \s+ 1\n
             $/