run-dev: Fix dev url showing extra port.
run-dev: Fix dev url showing extra port.

This commit fixes the issue of `run-dev.py`
showing the development URL with an
extra port when EXTERNAL_HOST
is specified.

Fixes: #17054

rht/zulip,rht/zulip,eeshangarg/zulip,eeshangarg/zulip,rht/zulip,punchagan/zulip,zulip/zulip,kou/zulip,andersk/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,eeshangarg/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,rht/zulip,hackerkid/zulip,andersk/zulip,zulip/zulip,punchagan/zulip,eeshangarg/zulip,andersk/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,zulip/zulip,kou/zulip,punchagan/zulip,zulip/zulip,rht/zulip,zulip/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,rht/zulip,kou/zulip,kou/zulip,hackerkid/zulip,kou/zulip,hackerkid/zulip,kou/zulip,punchagan/zulip,andersk/zulip,hackerkid/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,zulip/zulip