Taxonomy: Remove redundant caching from `get_all_category_ids()`, deprecated...

Taxonomy: Remove redundant caching from `get_all_category_ids()`, deprecated in favor of `get_terms()` in [28679].

The `all_category_ids` cache key it relied on was removed in [5555] and never repopulated, causing invalid or unexpected results when using a persistent object cache.

Props itowhid06, johnjamesjacoby.
Fixes #48176.
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