Fix gh-pages symlink (#1625)

It turns out that upload-artifacts strips broken symlinks:
actions/upload-artifact#93, so our approach of
generating a broken symlink that gets linked when it gets to gh-pages
doesn't work. We can work around this by using tarring the output before
uploading the artifacts, but it turns out that the "pages build and
deployment" action doesn't support broken symlinks either, because it
uses `--dereference` in its tar command:

<img width="680" alt="image"
src="https://github.com/WATonomous/infra-config/assets/5977478/c78c2152-f989-4dbc-84c2-daf9e4a89347">

The new strategy in this PR is to set up the symlinks only on master and
only in CI.

next.config.js

@@ -39,9 +39,7 @@ module.exports = withNextra({
 // const withExportImages = require('next-export-optimize-images')
 // module.exports = withExportImages(module.exports)
 
-
 // Injected content via Sentry wizard below
-
 const { withSentryConfig } = require("@sentry/nextjs");
 
 module.exports = withSentryConfig(

scripts/post-build.sh

@@ -9,9 +9,6 @@ echo "Running post-build commands..."
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
 
-# We deploy all other projects to _deployments. This allows us to visit them using /project instead of /_deployments/project.
-ln -s "_deployments/onboarding-form" "$PROJECT_DIR/out/onboarding-form-test"
-
 # Optimize images
 # https://next-export-optimize-images.vercel.app/docs/getting-started
 # Disabled for now, because the generated images are often larger than the originals.