refactor port binding access

[WolfgangFahl]

pb_dict=mw.container.host_config.port_bindings
            p80="80/tcp"
            if p80 in pb_dict:
                pb=pb_dict[p80][0]
                host_port=pb.host_port
                Logger.check_and_log_equal(f"port binding",host_port,"expected  port",str(self.config.port))
                url=self.config.url
                # fix url to local port
                url=url.replace(str(self.config.port),host_port)
                version_url=f"{url}/index.php/Special:Version"

                ok=self.checkWiki(version_url)
                if not ok:
                    exitCode=1
            else:
                self.log(f"port binding {p80} missing",False)
                exitCode=1
            pass

the 80 binding is only for the mediawiki container the db container has the same at 3306