Fix erroneous resetting of profiler state to undefined (#3394)

Author: szegedi

packages/dd-trace/src/profiling/profilers/wall.js

@@ -127,7 +127,6 @@ class NativeWallProfiler {
       this._profilerState = this._pprof.time.getState()
       this._currentContext = {}
       this._pprof.time.setContext(this._currentContext)
-      this._profilerState = undefined
       this._lastSpan = undefined
       this._lastStartedSpans = undefined
       this._lastSampleCount = 0