Fix: File block add custom class (#13432)

## Description
The custom class should only be added to the wrapper, not every div
Fixes #13430

packages/block-library/src/file/edit.js

@@ -184,9 +184,9 @@ class FileEdit extends Component {
 					</MediaUploadCheck>
 				</BlockControls>
 				<div className={ classes }>
-					<div className={ `${ className }__content-wrapper` }>
+					<div className={ 'wp-block-file__content-wrapper' }>
 						<RichText
-							wrapperClassName={ `${ className }__textlink` }
+							wrapperClassName={ 'wp-block-file__textlink' }
 							tagName="div" // must be block-level or else cursor disappears
 							value={ fileName }
 							placeholder={ __( 'Write file name…' ) }
@@ -195,11 +195,11 @@ class FileEdit extends Component {
 							onChange={ ( text ) => setAttributes( { fileName: text } ) }
 						/>
 						{ showDownloadButton &&
-							<div className={ `${ className }__button-richtext-wrapper` }>
+							<div className={ 'wp-block-file__button-richtext-wrapper' }>
 								{ /* Using RichText here instead of PlainText so that it can be styled like a button */ }
 								<RichText
 									tagName="div" // must be block-level or else cursor disappears
-									className={ `${ className }__button` }
+									className={ 'wp-block-file__button' }
 									value={ downloadButtonText }
 									formattingControls={ [] } // disable controls
 									placeholder={ __( 'Add text…' ) }
@@ -213,7 +213,7 @@ class FileEdit extends Component {
 						<ClipboardButton
 							isDefault
 							text={ href }
-							className={ `${ className }__copy-url-button` }
+							className={ 'wp-block-file__copy-url-button' }
 							onCopy={ this.confirmCopyURL }
 							onFinishCopy={ this.resetCopyConfirmation }
 							disabled={ isBlobURL( href ) }