[Minor]improvement(catalog-paimon):Fix irregular variable names (#4110)

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

Fix irregular variable names: tablename -> tableName

### Why are the changes needed?

Variable name `tablename` is irregular

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

Modify variable name naming convention, no testing required.

catalogs/catalog-lakehouse-paimon/src/main/java/com/datastrato/gravitino/catalog/lakehouse/paimon/ops/PaimonCatalogOps.java

@@ -74,9 +74,9 @@ public Table loadTable(String tableName) throws TableNotExistException {
     return catalog.getTable(tableIdentifier(tableName));
   }
 
-  public void createTable(String tablename, Schema schema)
+  public void createTable(String tableName, Schema schema)
       throws Catalog.TableAlreadyExistException, DatabaseNotExistException {
-    catalog.createTable(tableIdentifier(tablename), schema, false);
+    catalog.createTable(tableIdentifier(tableName), schema, false);
   }
 
   public void dropTable(String tableName) throws TableNotExistException {