Revert "Record when block was fully received"

Summary:
This reverts commit eb27c4cab51918b6daee5238017da309eb92289a.
nTimeBlockReceived should be set at the end of AcceptBlock.

Test Plan:

make VERBOSE=1 check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D2138