Fix WallClockASGCT::timerLoop skipping every other thread

Remove the spurious extra ThreadList::next() call in the no-filter
fallback branch of collectThreads. The loop already reads one tid per
iteration via the hasNext()/next() pattern; the trailing next() advanced
the cursor a second time, so tids was populated with only the 1st, 3rd,
5th, ... entries.

Impact: when threadFilter->enabled() is false, wallclock ticks sampled
only half of eligible threads. The context-filtered path is unaffected.

JIRA: PROF-14332

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jbachorik

ddprof-lib/src/main/cpp/wallClock.cpp

@@ -170,7 +170,6 @@ void WallClockASGCT::timerLoop() {
           if (tid != OS::threadId()) {
             tids.push_back(tid);
           }
-          tid = thread_list->next();
         }
         delete thread_list;
       }