scripted-diff: Rename recentRejects

Summary:

-BEGIN VERIFY SCRIPT-
ren() { sed -i "s:\<$1\>:$2:g" $(git grep -l "\<$1\>" ./src ./test); }

ren recentRejects m_recent_rejects
-END VERIFY SCRIPT-

This is a partial backport of core#21562
https://github.com/bitcoin/bitcoin/pull/21562/commits/37dcd12d539e4a875581fa049aa0f7fafeb932a4

Depends on D13378

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D13379