Remove resetSequence()

The only driver that needed it was postgres. However, using truncate
with RESET IDENTITY will force automatically reset the related
sequences.

lib/Cake/Database/Connection.php

@@ -431,19 +431,6 @@ public function rollbackSavepoint($name) {
 		$this->execute($this->_driver->rollbackSavePointSQL($name));
 	}
 
-/**
- * Reset a sequence.
- *
- * Useful with database platforms that support sequences.
- *
- * @param string $table The table to reset.
- * @param string $key The key to reset.
- * @return boolean
- */
-	public function resetSequence($table, $key) {
-		// TODO implement this.
-	}
-
 /**
  * Quotes value to be used safely in database query
  *

lib/Cake/TestSuite/Fixture/TestFixture.php

@@ -282,16 +282,7 @@ public function insert(Connection $db) {
 				$query->values($row);
 			}
 
-			$result = $query->execute();
-
-			$primary = $this->_schema->primaryKey();
-			if (
-				count($primary) == 1 &&
-				in_array($this->_schema->column($primary[0])['type'], ['integer', 'biginteger'])
-			) {
-				$db->resetSequence($this->table, $primary[0]);
-			}
-			return $result;
+			return $query->execute();
 		}
 		return true;
 	}