raise KeyError if no default is provided and the key doesn't exist

(and PILLAR_RAISE_ON_MISSING setting is true-ish)
Merge branch 'safe-pillar-get' of https://github.com/Lacrymology/salt into Lacrymology-safe-pillar-get
cange to lowercase
Merge pull request #19179 from thatch45/Lacrymology-safe-pillar-get

Merge #19122 with config change