DocumentSymbolCache: Don't schedule duplicate requests

Avoid scheduling a new request for the uri when
a request for the same uri is currently running.

Change-Id: Iac056b275c62e8640bf43a0ec9b6b6561b44eaed
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/languageclient/documentsymbolcache.cpp

@@ -40,6 +40,8 @@ DocumentSymbolCache::DocumentSymbolCache(Client *client)
 
 void DocumentSymbolCache::requestSymbols(const DocumentUri &uri, Schedule schedule)
 {
+    if (m_runningRequests.contains(uri))
+        return;
     m_compressedUris.insert(uri);
     switch (schedule) {
     case Schedule::Now: