Remove computed deep each

[nlfurniss]

Part of #19662
ember-metal.computed-deep-each
Tests pass locally

The code in getChainTags was deleted because it seems that that condition won't be reached since setting a deep dependent key will throw an error before it can be geted.

[mixonic]

@pzuraq This could use your eyes. I'm not sure which site should be changed to raise the error, and if the error should be a hard throw or simply a dev-only assert. As this code is performance sensitive, dev-only seems fine by my own intuition, but I'd like more feedback.

[pzuraq]

This should be a dev-only assert, definitely. I believe the location of the new error is correct though, it should catch both cases and properly prevent them (since the each case is a special case of the nested chaining case)

[nlfurniss]

This should be a dev-only assert, definitely. I believe the location of the new error is correct though, it should catch both cases and properly prevent them (since the each case is a special case of the nested chaining case)

Sounds good, updated

[mixonic]

This looks great to me, I pushed a rebase of the branch to address a conflict and will merge.