fix: remove legacy xmodulemixin from xblocks-contrib xblocks

[irtazaakram]

Relevant PR in xblocks-contrib: openedx/xblocks-contrib#230

[irtazaakram]

TODO: Revert these flags before merging

[kdmccormick]

You need to add this because XModuleMixin was missing from modulestore-based tests, right?

For modulestore-based app code, the mixins are being added here:

openedx-platform/xmodule/modulestore/django.py

Line 321 in dc6e19e

xblock_mixins=getattr(settings, 'XBLOCK_MIXINS', ()),

Do you know why that isn't working for tests? Ideally, we should only add XBLOCK_MIXINS in one place.

[irtazaakram]

It was XMLModuleStore's tests that were failing. I've reverted this change and made this addition to tests so we are only adding it in one place.

[kdmccormick]

Code is crashing on the following test sceneario, it's working fine on the master/main branch.
Test Scenario: Add Video Component (Block) in the Content Library

Right, this is the scenario I was talking about in sync: The new runtime intentionally does not add XModuleMixin because we are trying to keep the legacy attributes out of new runtime code. Content Libraries uses this runtime. We have two options:

1. We remove the usage of just enough legacy attributes so that Content Libraries can continue to work without XModuleMixin.
2. We temporarily add XModuleMixin to the new runtime, with a TODO comment and a link to a followup issue.

Of course (1) is preferred if it's easy. But if (1) would mean that the refactoring would go past next Wednesday, then go with (2).

Let me know if you'd like help debugging or deciding which option to do.

[farhan]

Code is crashing on the following test sceneario, it's working fine on the master/main branch.
Test Scenario: Add Video Component (Block) in the Content Library

Right, this is the scenario I was talking about in sync: The new runtime intentionally does not add XModuleMixin because we are trying to keep the legacy attributes out of new runtime code. Content Libraries uses this runtime. We have two options:

1. We remove the usage of just enough legacy attributes so that Content Libraries can continue to work without XModuleMixin.
2. We temporarily add XModuleMixin to the new runtime, with a TODO comment and a link to a followup issue.

Of course (1) is preferred if it's easy. But if (1) would mean that the refactoring would go past next Wednesday, then go with (2).

Let me know if you'd like help debugging or deciding which option to do.

I moved the comment in this PR

I think we can spend limited time in exploring 1 or 2 cases if it found extra complex then let's go for point 2 now and create a story with details for point 1

For example: usage of bind_for_student for VideoBlock in content library

Perhaps we have option 3 as well:
3. Move all the methods back to the XBlocks which are needed to run XBlocks in the content-library without attaching XModuleMixin to content library runtime.