Change reporter.panic to reporter.panicOnBuild

Fixes issue gatsbyjs#37557 so gatsby develop runs successfully even if Image CDN field generation fails for a particular image

packages/gatsby-source-drupal/src/normalize.ts

@@ -131,7 +131,7 @@ const getGatsbyImageCdnFields = async ({
         2
       )
     )
-    reporter.panic(
+    reporter.panicOnBuild(
       `[gatsby-source-drupal] Encountered an unrecoverable error while generating Gatsby Image CDN fields for url ${url}. See above for additional information.`
     )
   }