test: Bump timeouts to avoid valgrind failures

Summary:
Backport of core#18345.

The sync_all timeout has been removed by later backport and is irrelevant.

Test Plan:

ninja all check-functional

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D12215