build: stop suffixing XModule SCSS with hashes

Similar to openedx#32287,
this change removes another unnecessary step from the
`xmodule_assets` script. The script, which generates XModule
SCSS "entrypoint" files (synthesizing one or more "source" SCSS
resources), was appending MD5 hashes to each SCSS entrypoint filename:

    common/static/xmodule/descriptors/scss:
       AboutBlockStudio.768623f4d8d73dfb637fc94583adb990.scss
       ...
       WordCloudBlockStudio.d41d8cd98f00b204e9800998ecf8427e.scss
    common/static/xmodule/modules/scss:
       AboutBlockPreview.05a6cbd5c10100a245fa2cbf151b9770.scss
       ...
       WordCloudBlockPreview.7b899a56a70d29c58cf14b7e1888a0ec.scss

It's unclear why these MD5 hashes needed to be appended.
A comment in xmodule/static_content.py hints that it might have
something to do with de-duplication, but that doesn't make any sense,
because each XModule has exactly two SCSS entrypoint files (one for
studio_view and one for other student/author_views) and none of those
entrypoint files can possibly be shared between XModules.

Soon, as part of deleting the `xmodule_assets` script,
we would like to just check these SCSS files into version control
rather than generating them. In order to do that, we will need to
drop the hashes. This commit does that.
The new output looks like this:

    common/static/xmodule/descriptors:
       AboutBlockStudio.scss
       ...
       WordCloudBlockStudio.scss
    common/static/xmodule/modules:
       AboutBlockPreview.scss
       ...
       WordCloudBlockPreview.scss

Part of: openedx#32292

xmodule/static_content.py

@@ -150,9 +150,8 @@ def _write_styles(selector, output_root, classes, css_attribute, suffix):
         ))
         module_styles_lines.extend(f'  @import "{name}";' for name in fragment_names)
         module_styles_lines.append('}')
-        file_hash = hashlib.md5("".join(fragment_names).encode('ascii')).hexdigest()
 
-        contents[f"{class_.__name__}{suffix}.{file_hash}.scss"] = '\n'.join(module_styles_lines)
+        contents[f"{class_.__name__}{suffix}.scss"] = '\n'.join(module_styles_lines)
 
     _write_files(output_root, contents)
 

xmodule/util/xmodule_django.py

@@ -61,9 +61,9 @@ def load_assets(self):
                             'path': '/openedx/edx-platform/common/static/bundles/AnnotatableBlockPreview.js.map'
                         },
                         {
-                            'name': 'AnnotatableBlockPreview.85745121.css',
-                            'path': 'common/static/css/xmodule/AnnotatableBlockPreview.85745121.css',
-                            'publicPath': '/static/css/xmodule/AnnotatableBlockPreview.85745121.css'
+                            'name': 'AnnotatableBlockPreview.css',
+                            'path': 'common/static/css/xmodule/AnnotatableBlockPreview.css',
+                            'publicPath': '/static/css/xmodule/AnnotatableBlockPreview.css'
                         }
                     ],
                     ...