ci: do not try to publish directories that are not packages (angular#…

…41393)

We now include `misc/angular-in-memory-web-api` in the packages that
are build in the `dist/packages-dist` directory. But this package should
not be published as an artifact.

This commit prevents attempting to publishing the `misc` directory by
first checking whether the directory contains a `package.json` file.

PR Close angular#41393

scripts/ci/publish-build-artifacts.sh

@@ -92,6 +92,12 @@ function publishPackages {
 
   for dir in $PKGS_DIST/*/
   do
+    if [[ ! -f "$dir/package.json" ]]; then
+      # Only publish directories that contain a `package.json` file.
+      echo "Skipping $dir, it does not contain a package to be published."
+      continue
+    fi
+
     COMPONENT="$(basename ${dir})"
 
     # Replace _ with - in component name.