[JNI] Cleanup MemoryBuffer/ColumnVector close methods to use common code

@gerashegalov had a comment in https://github.com/rapidsai/cudf/pull/15351 that I thought would make sense as a follow on. Specifically, we'd like to make a utility available in the JNI code so that classes that need to invoke `onClosed` can do so with the same common code.

This is now inconsistent with (Host)ColumnVector. If we cannot consistently move eventHandler.onClosed into a finally please add a comment, but hopefully we can and it could be generalized via some utls withEventHandler(eventHandler) or base class implementation.

_Originally posted by @gerashegalov in https://github.com/rapidsai/cudf/pull/15351#discussion_r1532615825_

Start by locating the JNI implementations of MemoryBuffer and ColumnVector and their close methods, then compare how each invokes eventHandler.onClosed. The work is done when both classes use a common utility or base implementation with consistent cleanup behavior, or the differing finally handling is explicitly documented.

Written by the indexing model from the issue text.