Remove redundant listen on haproxy handler

Follow-up on [1] "Avoid multiple haproxy restarts after
reconfiguration".

There is no need to duplicate handler name in listen.
The issue was because we had two handlers with the same
name in the same environment.
This causes Ansible not to mark handler as already run.

[1] https://review.opendev.org/708385

Change-Id: I5425a8037b6860ef71bce59becff8dfe5b601d4c
Related-Bug: #1864810