Revise destination name generation mechanism when building outlines

Previously, prefix was duplicated which resulted in named like
"pdfHTML-iText-outline-pdfHTML-iText-outline-1"

DEVSIX-3495

Autoported commit.
Original commit hash: [69a8e214]

Author: Snipx

itext.tests/itext.html2pdf.tests/itext/html2pdf/attach/impl/OutlineHandlerTest.cs

@@ -53,8 +53,7 @@ public virtual void DefaultDestinationPrefixTest() {
             PdfOutline pdfOutline = context.GetPdfDocument().GetOutlines(false).GetAllChildren()[0];
             NUnit.Framework.Assert.AreEqual("p1", pdfOutline.GetTitle());
             PdfString pdfStringDest = (PdfString)pdfOutline.GetDestination().GetPdfObject();
-            NUnit.Framework.Assert.AreEqual("pdfHTML-iText-outline-pdfHTML-iText-outline-1", pdfStringDest.ToUnicodeString
-                ());
+            NUnit.Framework.Assert.AreEqual("pdfHTML-iText-outline-1", pdfStringDest.ToUnicodeString());
         }
 
         [NUnit.Framework.Test]
@@ -78,7 +77,7 @@ public virtual void CustomDestinationPrefixTest() {
             PdfOutline pdfOutline = context.GetPdfDocument().GetOutlines(false).GetAllChildren()[0];
             NUnit.Framework.Assert.AreEqual("p1", pdfOutline.GetTitle());
             PdfString pdfStringDest = (PdfString)pdfOutline.GetDestination().GetPdfObject();
-            NUnit.Framework.Assert.AreEqual("prefix-prefix-1", pdfStringDest.ToUnicodeString());
+            NUnit.Framework.Assert.AreEqual("prefix-1", pdfStringDest.ToUnicodeString());
         }
     }
 }

itext.tests/itext.html2pdf.tests/resources/itext/html2pdf/css/PageRuleTest/cmp_marginBoxRunningOutlines01.pdf

@@ -186,7 +186,7 @@ public virtual String GetDestinationNamePrefix() {
         /// <param name="element">the element</param>
         /// <returns>the unique destination name</returns>
         protected internal virtual String GenerateUniqueDestinationName(IElementNode element) {
-            return destinationNamePrefix + GetUniqueID(destinationNamePrefix);
+            return GetUniqueID(destinationNamePrefix);
         }
 
         /// <summary>Generate the unique outline name.</summary>

itext.tests/itext.html2pdf.tests/resources/itext/html2pdf/css/PageRuleTest/cmp_marginBoxRunningOutlines02.pdf

@@ -1 +1 @@
-d0f3df080977a62243ceeab41242fff9402dde59
+69a8e214688a8b3f38ecf42ea7f5e1ebfc7211ca