downloader: unexpected error if the repomgr.stx_mirror_strategy=upstream

[Jackie Huang]

Brief Description
-----------------
Setting repomgr.stx_mirror_strategy to "upstream", then the downloader failed with:
NameError: name 'urstx_mirror' is not defined

Severity
--------
Minor

Steps to Reproduce
------------------
(1)
stx config --add repomgr.stx_mirror_strategy upstream
stx config --upgrade

(2) Check stx.conf
grep stx_mirror_strategy stx.conf

(3) Run download in builder pod
downloader

Expected Behavior
------------------
downloader run successfully

Actual Behavior
----------------
Traceback (most recent call last):
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/downloader", line 740, in <module>
    binary_dl.start()
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/downloader", line 557, in start
    self.download_list_files(repo, self.layer_binaries[layer])
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/downloader", line 407, in download_list_files
    self.download_list(repo, pkg_data)
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/downloader", line 464, in download_list
    ret = self.download(debnames[0], debnames[1], url)
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/downloader", line 279, in download
    (dl_url, alt_dl_url) = utils.get_download_url(url, STX_MIRROR_STRATEGY)
  File "/localdisk/designer/jhuang0/prj-stx-deb/cgcs-root/build-tools/stx/utils.py", line 199, in get_download_url
    rt_url = urstx_mirror
NameError: name 'urstx_mirror' is not defined

Reproducibility
---------------
Reproducible

System Configuration
--------------------
N/A

Branch/Pull Time/Commit
-----------------------
master/2023-11-28

Last Pass
---------
N/A

Timestamp/Logs
--------------
N/A

Test Activity
-------------
N/A

Workaround
----------
N/A

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/root/+/903132

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/root/+/903132
Committed: https://opendev.org/starlingx/root/commit/d9705916d19a91d52926fb67eebbae1237d7cc15
Submitter: "Zuul (22348)"
Branch: master

commit d9705916d19a91d52926fb67eebbae1237d7cc15
Author: Jackie Huang <email address hidden>
Date: Fri Dec 8 15:42:04 2023 +0800

    iutils.py: fix typo for upstream url

    'urstx_mirror' doesn't exist and was introduced
    in previous commit.

    Closes-bug: 2044987

    Change-Id: I020acd6c8fb0c0aab0911542f8f1af4d27be9b2c
    Signed-off-by: Jackie Huang <email address hidden>