Remove Arclight URL matching on %2F style arc urls

[amywieliczka]

Arclight routes currently match arks that look like /findaid/ark:/12345/abcdefg and /findaid/ark:%2F12345%2Fabcdefg - update the ark constraint regex so it no longer matches %2F style arks.

[amywieliczka]

cloudfront logs filtered for %2F in the past day - 2,191 today

arclight logs filtered for %2F in the past hour - 29,907 today