Move method PollerParser.configureTransactionAttributes to IntegrationNamespaceUtils

For the JPA Adapter I copied a method:

from org.springframework.integration.config.xml.PollerParser because the respective method is private. We need to move the method "configureTransactionAttributes" to IntegrationNamespaceUtils to eliminate code duplication.

Currently the copied method resides in:

org.springframework.integration.jpa.config.xml.JpaParserUtils

public static BeanDefinition configureTransactionAttributes(Element txElement)