fix: Update for new version of demo course

[timmc-edx]

In https://github.com/openedx/openedx-demo-course/pull/47 the demo course was replaced. This includes a new course key (new name and org) and the course content being moved a few directories deeper. (Ticket: https://github.com/openedx/devstack/issues/1273)

Changes:

• sed -i 's/course-v1:edX+DemoX+Demo_Course/course-v1:Axim+DemoX+demo_course/g' on all files turned up by grep -rl Demo_Course
• Updated a few other course info locations turned up with grep -nrI DemoX | grep -x demo_course (all in programs/discovery.py)
• Updated git clone URL and checkout location in provision-lms.sh to use new repo name (not strictly needed).

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I've completed each of the following or determined they are not applicable:

• [x] Made a plan to communicate any major developer interface changes (or N/A)

[timmc-edx]

Only failing for ecommerce+lms. There are still conflicting demo course references somewhere. I had hoped to fix this by changing mentions of edX as a partner in provision-ecommerce.sh along with changes in https://github.com/openedx/ecommerce/compare/master...timmc-edx:ecommerce:timmc/new-demo-course but no luck -- there are now duplicate partner code entries. Maybe requires reverting the SQL changes in this PR and re-running update-dbs-init-sql-scripts.sh with just the right changes to partner codes in devstack and ecommerce?