@Jdforrester-WMF, hard deprecation patch up! Can still stop a few places where this is used: https://codesearch.wmflabs.org/search/?q=(%3A%3A%7C-%3E)transformSearchTerm&i=nope&files=&repos=, once they're cleaned up, removal is safe! Thanks
It was already removed, and it was done so in 1.34. It was mistakenly specified as hard-deprecated in 1.32 which is when it was soft-deprecated, and thus confusingly removed too soon within the same cycle.