test: check for matching object hashes in wait_for_getdata

Summary:

Previously, wait_for_getdata only looked for the presence of a recent "getdata" message. Additionally checking the object hashes inside the message should make tests involving wait_for_getdata more robust.

p2p_sendheaders.py already overrides wait_for_getdata do this check; we can use the same approach consistently across all tests that call wait_for_getdata.

This is a backport of Core PR18690

Test Plan: ninja check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8961