Block Directory: Remove the author rating when none exist (#22184)

A `0` rating means there have been no reviews submitted, so we can omit this string.

packages/block-directory/src/components/downloadable-block-author-info/index.js

@@ -19,16 +19,26 @@ function DownloadableBlockAuthorInfo( {
 				) }
 			</span>
 			<span className="block-directory-downloadable-block-author-info__content">
-				{ sprintf(
-					/* translators: 1: number of blocks. 2: average rating. */
-					_n(
-						'This author has %1$d block, with an average rating of %2$d.',
-						'This author has %1$d blocks, with an average rating of %2$d.',
-						authorBlockCount
-					),
-					authorBlockCount,
-					authorBlockRating
-				) }
+				{ authorBlockRating > 0
+					? sprintf(
+							/* translators: 1: number of blocks. 2: average rating. */
+							_n(
+								'This author has %1$d block, with an average rating of %2$d.',
+								'This author has %1$d blocks, with an average rating of %2$d.',
+								authorBlockCount
+							),
+							authorBlockCount,
+							authorBlockRating
+					  )
+					: sprintf(
+							/* translators: 1: number of blocks. */
+							_n(
+								'This author has %1$d block.',
+								'This author has %1$d blocks.',
+								authorBlockCount
+							),
+							authorBlockCount
+					  ) }
 			</span>
 		</Fragment>
 	);