chore(auth): Remove skipConfirmationForEmailAddresses config

Because:
 - We added the new skipConfirmationForEmailRegex
 - And we don't want multiple ways to manage skipping sign in
   confirmation emails

This Commit:
 - Removes the older config
 - Removes associated tests

Closes: FXA-13360

Author: nshirley

packages/fxa-auth-server/config/index.ts

@@ -1687,14 +1687,8 @@ const convictConf = convict({
       default: /.+@mozilla\.com$/,
       env: 'SIGNIN_CONFIRMATION_FORCE_EMAIL_REGEX',
     },
-    skipForEmailAddresses: {
-      doc: 'Comma separated list of email addresses that will always skip any non TOTP sign-in confirmation',
-      format: Array,
-      default: [],
-      env: 'SIGNIN_CONFIRMATION_SKIP_FOR_EMAIL_ADDRESS',
-    },
     skipForEmailRegex: {
-      doc: 'Regex pattern for email addresses that will always skip any non-TOTP sign-in confirmation. Checked in addition to skipForEmailAddresses.',
+      doc: 'Regex pattern for email addresses that will always skip any non-TOTP sign-in confirmation.',
       format: RegExp,
       default: /^$/,
       env: 'SIGNIN_CONFIRMATION_SKIP_FOR_EMAIL_REGEX',