Rewrite comments for correctness and clarity in AttributeRemover

- Improved comment clarity and accuracy regarding the conditions for not leaving an empty line after removing an attribute.
- Corrected the discrepancy between the comment and the implementation concerning the presence of leading trivia in the next token.
- Refined the explanation about the significance of trailing trivia when attributes are not separated by trivia.

Author: gohanlon

Sources/SwiftSyntaxMacroExpansion/MacroSystem.swift

@@ -398,28 +398,33 @@ private class AttributeRemover: SyntaxRewriter {
     for case .attribute(let attribute) in node {
       if attributesToRemove.contains(attribute) {
         var leadingTrivia = attribute.leadingTrivia
+
+        // Don't leave behind an empty line when the attribute being removed is on its own line,
+        // based on the following conditions:
+        //  - Leading trivia ends with a newline followed by arbitrary number of spaces or tabs
+        //  - All leading trivia pieces after the last newline are just whitespace, ensuring
+        //    there are no comments or other non-whitespace characters on the same line
+        //    preceding the attribute.
+        //  - There is no trailing trivia and the next token has leading trivia.
         if let lastNewline = leadingTrivia.pieces.lastIndex(where: \.isNewline),
           leadingTrivia.pieces[lastNewline...].allSatisfy(\.isWhitespace),
           attribute.trailingTrivia.isEmpty,
           let nextToken = attribute.nextToken(viewMode: .sourceAccurate),
           !nextToken.leadingTrivia.isEmpty
         {
-          // If the attribute is on its own line based on the following conditions,
-          // remove the newline from it so we don’t end up with an empty line
-          //  - Leading trivia ends with a newline followed by arbitrary number of spaces or tabs
-          //  - There is no trailing trivia and the next token has no leading trivia
           leadingTrivia = Trivia(pieces: leadingTrivia.pieces[..<lastNewline])
         }
+
         // Drop any spaces or tabs from the trailing trivia because there’s no
         // more attribute they need to separate.
         let trailingTrivia = attribute.trailingTrivia.trimmingPrefix(while: \.isSpaceOrTab)
         triviaToAttachToNextToken += leadingTrivia + trailingTrivia
 
-        // If the attribute is not separated by the previous attribute using trivia, e.g.
-        // `@First@Second var x: Int` (yes, that's valid Swift), and removing  the `@Second`
-        // attribute then dropping all trivia of this attribute would join `@First` and `var`
-        // without any trivia in between, which is invalid. In this case the trailing trivia of the
-        // attribute is significant and we need to keep it.
+        // If the attribute is not separated from the previous attribute by trivia, as in
+        // `@First@Second var x: Int` (yes, that's valid Swift), removing the `@Second`
+        // attribute and dropping all its trivia would cause `@First` and `var` to join
+        // without any trivia in between, which is invalid. In such cases, the trailing trivia
+        // of the attribute is significant and must be retained.
         if triviaToAttachToNextToken.isEmpty,
           let previousToken = attribute.previousToken(viewMode: .sourceAccurate),
           previousToken.trailingTrivia.isEmpty