IcebergCatalogAdapter: close underlying catalog consistently (#1224)

With the revert of #b84f4624db8d0bd5b8920b0df719bcc15666008f by #ccf25df7b055e9d232b88a3f6fe8b4e0a2ab035a, we lost an extra benefit that was included in that change: a fix for the fact that IcebergCatalogHandlerWrapper does not always close its underlying `Catalog`, thus relying on `CallContext` to play the role of the "sweep vehicle" and close everything that was left unclosed at the end of the request processing.

This PR re-applies that fix again.

Author: adutra