fix: oracle cannot support DB in table identifiers (#7954)

oracle queries cannot support the identifier including the database in this way (`XE.SYSTEM.table`)

Instead, if you should specify a separate database a link must be set up and then
the database link identifier is included after the table. (`SYSTEM.table@XE`)

However, because that's rather difficult to set up lets not for now & just prevent
inclusion of the database in the case that we fetch it.

src/driver/oracle/OracleDriver.ts

@@ -355,10 +355,6 @@ export class OracleDriver implements Driver {
             tablePath.unshift(schema);
         }
 
-        if (database) {
-            tablePath.unshift(database);
-        }
-
         return tablePath.join('.');
     }