Fix the curl commands for metadata fetches.
Fix the curl commands for metadata fetches.

Add -f to "fail silently", instead of returning an html 404 page on not-found;
otherwise, not-found keys cause the variable to interpret the html text as
an actual value. Also add -s to eliminate download-status cruft from the output.

Caserta-Concepts/dataproc-initialization-actions,Caserta-Concepts/dataproc_init,GoogleCloudDataproc/initialization-actions,GoogleCloudDataproc/initialization-actions,dennishuo/dataproc-initialization-actions,pmkc/dataproc-initialization-actions,jmbejara/dataproc-initialization-actions,jmbejara/dataproc-initialization-actions,lukeFalsina/dataproc-initialization-actions,dennishuo/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions,pmkc/dataproc-initialization-actions,Caserta-Concepts/dataproc-initialization-actions,lukeFalsina/dataproc-initialization-actions,Caserta-Concepts/dataproc_init