run_tests.sh in horizon-reload.sh no longer exists in horizon master

[Akihiro Motoki]

horizon master (for Queens) dropped run_tests.sh in favor of tox.
horizon-reload.sh in "Running DevStack" section should be updated accordingly.
python manage.py compilemessage does the same.

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

- [ ] This doc is inaccurate in this way: ______
- [ ] This is a doc addition request.
- [x] I have a fix to the document that I can paste below including example: input and output.

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-----------------------------------
Release: on 2017-08-17 23:27
SHA: b93528ca263385f4caaf4dba2ce84a4e06dccf90
Source: https://git.openstack.org/cgit/openstack/i18n/tree/doc/source/check_translation.rst
URL: https://docs.openstack.org/i18n/latest/check_translation.html

[Ian Y. Choi (ianychoi)]

Addressed by https://review.openstack.org/#/c/494979/