Fix extra parenthesis in python .format()

Summary:
Some python .format() lines have extra parenthesis, which is causing
an exception to throw when a tuple is not expected.

Test Plan:

ninja check-functional

The changes have been evaluated in a python console to make sure it
outputs what is expected.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D4899