Remove the entry with old id from the cache

[marcin-krystianc]

Fixes #4778

This PR addresses a subtle issue in handling topic IDs during metadata cache insertion. Separating this condition ensures that old entries with non-zero topic IDs are always properly removed from the metadata cache.
Removing the entry from the rkmc_avl tree but not removing the old entry with non-zero topic IDs from the rkmc_avl_by_id tree led to an inconsistent cache state. Eventually, it led to memory corruption ("use after free" errors).

Testing

My test application re-creates (deletes and creates) three thousand topics. Then it immediately starts producer and consumer threads. Before the fix, the app crashed most of the time, after the fix crashes do not happen anymore.

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✅ marcin-krystianc
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