[cleanup] Clarify sanitized pattern and set threshold to accurate 51/100
[cleanup] Clarify sanitized pattern and set threshold to accurate 51/100

These are mostly alignments to bring it closer to the Bitcoin Core version of
this script, which eliminates some unnecessary incrementing/decrementing
by one and also has clearer use of constants.

BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited