Disable JDBC auto-commit on new connections

ojdbc17 23.x defaults auto-commit to true (per JDBC spec), while older
Oracle drivers defaulted to false. The gem relies on explicit commit
and rollback, so every commit call raised ORA-17273 on JRuby CI.

Set setAutoCommit(false) explicitly after creating raw JDBC connections
in both the production code path and the spec test harness to restore
the long-standing behavior regardless of driver default.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yahonda

lib/plsql/jdbc_connection.rb

@@ -63,6 +63,7 @@ def self.create_raw(params)
           props.setProperty("password", params[:password])
         end)
       end
+      conn.setAutoCommit(false)
       new(conn)
     end
 

spec/spec_helper.rb

@@ -98,7 +98,7 @@ def get_connection(user_number = 0)
           props.setProperty("user", database_user)
           props.setProperty("password", database_password)
         end)
-      end
+      end.tap { |c| c.setAutoCommit(false) }
     end
   end
 end