Remove deprecated dropshadows

[MisRob]

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Blocked by

• https://github.com/learningequality/kolibri/issues/12552
• https://github.com/learningequality/kolibri-design-system/issues/724

Summary

For both internal KDS components styling and external use by non-KDS components in our products, according to the updated guidelines in the "Elevation and shadow > Drop shadows" documentation section, we only need to keep %dropshadow-1dp , %dropshadow-2dp , and %dropshadow-6dp in the definitions.scss:

https://github.com/learningequality/kolibri-design-system/blob/0cbdf57d24690cb6c23618ba700118a831cd9ffc/lib/styles/definitions.scss#L59-L157

All other %dropshadow-... should not be available for use.

Guidance

• I think it’d be fine to just comment them out rather than delete, in case we need some of them in the future - as long as there’s a note that uncommenting needs to be discussed with designers and should be aligned with the guidelines.
• Issues in "Blocked by" should be resolved first to ensure that KDS version upgrade is not demanding in Kolibri that has many drop shadows. Still needs to be communicated as a breaking change and consumers should double-check before installing the corresponding release (the issues mentioned should cover most of it, however there may be one or two places in Studio to update as well)

[lokesh-sagi125]

i've already finished commenting the deprecated drop shadows , can you assign this to me, so i can PR my changes?

[MisRob]

Thanks @lokesh-sagi125. I'll assign you. Just a note it's better to get assigned first in case some clarification is needed, so please always message us and wait for assignment.

Would you mind splitting https://github.com/learningequality/kolibri-design-system/pull/734 into two pull requests? One that resolves https://github.com/learningequality/kolibri-design-system/issues/724 and another that resolves this issue.

These are deliberately two issues because https://github.com/learningequality/kolibri-design-system/issues/724 can be merged soon, whereas for the other one we will be waiting until https://github.com/learningequality/kolibri/issues/12552, otherwise it'd break many places in Kolibri. We will then review both pull requests.