remove variant map after merge conflict

Author: nhsd-david-wass

lambdas/upsert-letter/src/config/env.ts

@@ -3,10 +3,6 @@ import { z } from "zod";
 const EnvVarsSchema = z.object({
   LETTERS_TABLE_NAME: z.string(),
   LETTER_TTL_HOURS: z.coerce.number().int(),
-  VARIANT_MAP: z.string().transform((str, _) => {
-    const parsed = JSON.parse(str);
-    return LetterVariantSchema.parse(parsed);
-  }),
   PINO_LOG_LEVEL: z.coerce.string().optional(),
 });