cloud-rad: Update comments to TSDoc syntax

[fhinkel]

As we're moving our ref docs to cloud.google.com, we're also changing the tooling: instead of working with JSDoc, we process TSDoc comments. Instead of defining a type in a comment, we need to annotate each variable. See e.g., this commit.

[surbhigarg92]

Since @dansaadati is working on making NodeJS doc stack healthy again, assigning the bug to him.