DevTools: Use default constructors/destructors

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#cother-other-default-operation-rules

"The compiler is more likely to get the default semantics right and
you cannot implement these functions better than the compiler."

Userland/DevTools/Profiler/TimelineView.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -18,10 +19,6 @@ TimelineView::TimelineView(Profile& profile)
     set_shrink_to_fit(true);
 }
 
-TimelineView::~TimelineView()
-{
-}
-
 u64 TimelineView::timestamp_at_x(int x) const
 {
     float column_width = (float)width() / (float)m_profile.length_in_ms();