Revert "fec.config: prefix paths"

I misunderstood, this is for legacy sourcemaps only, the new method uses
debug IDs which are embedded and don't rely on url paths to resolve the
sources.

This reverts commit 2410143ba0.

fec.config.js

@@ -61,7 +61,6 @@ if (process.env.SENTRY_AUTH_TOKEN) {
       authToken: process.env.SENTRY_AUTH_TOKEN,
       org: process.env.SENTRY_ORG,
       project: process.env.SENTRY_PROJECT,
-      urlPrefix: '~/apps/image-builder',
       _experiments: {
         moduleMetadata: ({ release }) => ({
           dsn: process.env.SENTRY_DSN,