This change fixes up several comments that accidentally used the JSDoc
tag @internal in regular block comments (`/*` instead of `/**`).
This prevents a problem with Closure Compiler that balks at `@` tags
occuring in regular block comments, because it assumes they were
intended to be tags for the compiler.
When occuring in `/**` JSDoc, tsickle escapes the tags, so they do not
cause problems.
PR Close#24928