As of the Ubuntu Code of Conduct v2.0, there is no longer a separate Leadership Code of Conduct. Instead, CoC 2.0 covers both.
Over the past two cycles the Community Council has put in a great deal
of effort to merge the original Code of Conduct with the very
important Leadership Code of Conduct so that the document more clearly
communicates the guiding principals the community has. That work has
involved two in-person sessions; one at UDS-Q and one at UDS-R. It has
also involved two drafts being shared with the community in an effort
to seek feedback. Every effort was made to clear up ambigous language
or phrases that posed difficulty to translations.
— Charles Profitt, "CoC Version 2.0 has been released" (official mailing list for Ubuntu News Team)
So now, the one CoC includes the expectations for leadership. And agreeing to CoC 2.0 corresponds to what was formerly achieved by agreeing both to CoC 1.1 and the Leadership CoC.
It makes sense that they are both collapsed into one as, after all, there are numerous opportunities for both participation and leadership in the Ubuntu community, most of which require no formal recognition (though some leadership positions are official, as always). CoC 2.0 makes this clear too:
We all lead by example, in debate and in action. We encourage new
participants to feel empowered to lead, to take action, and to
experiment when they feel innovation could improve the project.
Leadership can be exercised by anyone simply by taking action, there
is no need to wait for recognition when the opportunity to lead
presents itself.
— Ubuntu Code of Conduct v2.0