Fix: Pin urllib3 in OpenStack-related scripts

Fix: Pin urllib3 in OpenStack-related scripts

This change pins urllib3 to version 1.26.15 in all
OpenStack-related scripts to fix connection issues with
OpenStack API where connections are being aborted with
RemoteDisconnected errors. These errors occur specifically
during stack creation and deletion operations.

The version pinning ensures compatibility with the OpenStack
client libraries and is consistent with the approach used in
other scripts that interact with remote services.

Issue: IT-28704
Change-Id: I791c967670f28a28517c57d062834b78ec1712df
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>