Remove sed command from the DAST pipeline

To turn off html_mailto via the config file. The command 'sed -i "84 s/true/false/" /zap/xml/config.xml' is be used from within a DAST job to disable it. This hack can be removed once #230687 (closed) is closed which will happen in v1.24

#239304 (comment 401056948)

DAST v1.24 solves the performance problem with rule html_mailto, which means we will no longer need the sed command to disable the rule after upgrading to >1.24