[refactor] Prep for scripted-diff by removing some \ns which annoy sed.

Summary:
This is a redo of https://github.com/bitcoin/bitcoin/pull/15141/commits/7721ad64f40a0c67edefaaf7353264d78df8803e

I used some sed magic:

sed -n '/\.DoS(/{ :loop N; s/,\n\s*/, /; s/\n\s*//; /\.DoS(.*;/!b loop}; p' -i ../src/validation.cpp ../src/consensus/tx_verify.cpp

Test Plan: Loop at the result

Reviewers: #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D6729