Paragraph block: remove dead CSS (#19821)

packages/block-library/src/paragraph/editor.scss

@@ -1,16 +1,3 @@
-// Specific to the empty paragraph placeholder:
-// when shown on mobile and in nested contexts, one or more icons show up on the right.
-// This padding makes sure it doesn't overlap text.
-.block-editor-rich-text__editable.wp-block-paragraph:not(.is-selected) [data-rich-text-placeholder]::after {
-	display: inline-block;
-	padding-right: $icon-button-size * 3;
-
-	// In nested contexts only one icon shows up.
-	.wp-block .wp-block & {
-		padding-right: $icon-button-size;
-	}
-}
-
 .block-editor-block-list__block[data-type="core/paragraph"] p {
 	min-height: $empty-paragraph-height / 2;
 	line-height: $editor-line-height;