chore(httpreplay): specify localhost for proxy listener

[quartzmo]

closes: #7087

@codyoss Is httpreplay ever used remotely? Will this change cause issues for anyone?

(Note that the package docs for httpreplay state: "This package is EXPERIMENTAL and is subject to change or removal without notice.")

[codyoss]

@quartzmo I am not sure. We just use this package as a test utility. The default of listening on all unicast IPs seems fine imo -- but not an expert in this space. I think the user report can also be solved by playing with firewall perms on their machine perhaps as well if my translation was accurate. If you are feeling pretty confident that this will not break anything I am fine moving forward, or else I would say either just leave it. Thoughts?

[quartzmo]

If you are feeling pretty confident that this will not break anything I am fine moving forward, or else I would say either just leave it.

It doesn't break anything when used locally (meaning, when the httpreplay client and listener are running on the same host), which is my impression of how the tool is supposed to be used. I would like to go forward with this change for the benefit (at least) of the #7087 poster. On the slight chance that breakage is reported for a use case we are not aware of, then I think we can change it back again. As stated: "EXPERIMENTAL and is subject to change or removal without notice."