Remove SCRIPT_VERIFY_CHECKDATASIG_SIGOPS flag from script tests

Summary:
Now that the flag has no effect on the validity of OP_CHECKDATASIG in scripts,
it is unnecessary to pass it into script tests.

The fact that the flag does not affect validity of the opcode is tested in the
checkdatasig_tests.cpp unit tests, and the effect of the flag on sigops counting
is tested in sigopcount_tests.cpp

Test Plan: make check

Reviewers: deadalnix, markblundeberg, Fabien, #bitcoin_abc

Reviewed By: deadalnix, Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3140