Investigate if deleteNodeIndex should check for SqlContentEntityStorage

Problem/Motivation

@dww posted

Likely out of scope, but maybe #NeedsFollowup... inserting the index records is checking that we're using SqlContentEntityStorage for node storage. But here, we "blindly" try to delete things. Seems a little weird that these two methods don't use the same logic to determine if they need to do their job.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

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