fix(47733): omit JSDoc comment template suggestion on node with existing JSDoc (#47748)

src/services/jsDoc.ts

@@ -353,7 +353,8 @@ namespace ts.JsDoc {
         }
 
         const { commentOwner, parameters, hasReturn } = commentOwnerInfo;
-        if (commentOwner.getStart(sourceFile) < position) {
+        const commentOwnerJSDoc = hasJSDocNodes(commentOwner) && commentOwner.jsDoc ? lastOrUndefined(commentOwner.jsDoc) : undefined;
+        if (commentOwner.getStart(sourceFile) < position || commentOwnerJSDoc && commentOwnerJSDoc !== existingDocComment) {
             return undefined;
         }
 

tests/cases/fourslash/docCommentTemplateWithExistingJSDoc.ts

@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts' />
+
+/////** /**/ */
+////
+/////**
+//// * @param {string} a
+//// * @param {string} b
+//// */
+////function foo(a, b) {
+////    return a + b;
+////}
+
+verify.noDocCommentTemplateAt("");