Remove PostgreSQLSchemaManager::_getPortableSequencesList()

[morozov]

This code is redundant:

1. Concatenation of the schema name and the sequence name in a qualified name is already implemented in _getPortableSequenceDefinition():

   dbal/src/Schema/PostgreSQLSchemaManager.php

   Lines 367 to 371 in bd983fb

   	if ($sequence['schemaname'] !== 'public') {
   	$sequenceName = $sequence['schemaname'] . '.' . $sequence['relname'];
   	} else {
   	$sequenceName = $sequence['relname'];
   	}

2. Filtering the list according to the configuration is already implemented in listSequences():

   dbal/src/Schema/AbstractSchemaManager.php

   Line 196 in 2d388f0

   return $this->filterAssetNames($this->_getPortableSequencesList($sequences));