[#7520] fix: Deduplicate supportPartitions() call (#7539)

### What changes were proposed in this pull request?

This PR removes the redundant invocation of `table.supportPartitions()`
in `CatalogWrapper#doWithPartitionOps`.
Now, the method is called once and its result is cached in a local
variable.

### Why are the changes needed?

Calling `table.supportPartitions()` twice results in unnecessary
repeated look-ups.
Caching the result improves code readability and performance.

Fix:  #7520

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
No behavior change is expected.

Author: kitoha

core/src/main/java/org/apache/gravitino/catalog/CatalogManager.java

@@ -218,9 +218,10 @@ public <R> R doWithPartitionOps(
             Preconditions.checkArgument(
                 asTables() != null, "Catalog does not support table operations");
             Table table = asTables().loadTable(tableIdent);
+            SupportsPartitions partitionOps = table.supportPartitions();
             Preconditions.checkArgument(
-                table.supportPartitions() != null, "Table does not support partition operations");
-            return fn.apply(table.supportPartitions());
+                partitionOps != null, "Table does not support partition operations");
+            return fn.apply(partitionOps);
           });
     }