Fix the test suite.

Summary: Now that UAHF activated, several tests broke. I deleted the one to set the UAHFStart time via RPC as we want to remove this now that the fork happened. I also increased the start time for another test to make sure the test suite is green while things are getting fixed.

Test Plan:

make check

Reviewers: freetrader, #bitcoin_abc

Reviewed By: freetrader, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D406