These tests were totally broken:
- Only did 1 iteration because it set flags |= ENABLE_CHECKDATASIG at start
- Wasn't aware of SCRIPT_VERIFY_COMPRESSED_PUBKEYTYPE
- Missed some SCRIPT_VERIFY_NULLFAIL cases
Also I changed it to use pseudorandom flags generator since the original intent of 262000 iterations would have been way way too slow anyway. Runtime is now ~3 sec, would have been 3 minutes (dominating test_bitcoin runtime) if original iter count ever actually worked.