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GH-36981: [Go] Fix ipc reader leak (#36982)



### Rationale for this change

Previously the ipc reader was leaking allocations.

### What changes are included in this PR?

Call `Clear()` on the memo table on final release of the ipc reader.

### Are these changes tested?

Yes

### Are there any user-facing changes?

* Closes: #36981

Authored-by: thorfour <me@thor-hansen.com>
Signed-off-by: Matt Topol <zotthewizard@gmail.com>