RFR: 8278430 : Several tests use terminally deprecated System.runFinalization method

[Hima Bindu Meda]

This PR is to remove calls to deprecated method System.runFinalization.
Here is the list of module wise test cases affected by the removal:

**web**:
test.javafx.scene.web.LeakTest

**systemTests**:
test.memoryleak.JSCallbackMemoryTest 
test.javafx.embed.swing.SwingNodeDnDMemoryLeakTest
test.javafx.embed.swing.SwingNodeMemoryLeakTest
 test.javafx.scene.control.AccordionTitlePaneLeakTest 
test.javafx.scene.control.TabPaneHeaderLeakTest 
test.javafx.scene.shape.ShapeViewOrderLeakTest test.javafx.scene.shape.meshmanagercacheleaktest.MeshManagerCacheLeakApp test.javafx.stage.FocusedWindowTestBase --tests test.memoryleak.JSCallbackMemoryTest
test.robot.javafx.web.TooltipFXTest

**graphics**:
test.javafx.scene.SceneTest

**controls**:
 test.javafx.scene.control.ToggleButtonTest
test.javafx.scene.control.ControlAcceleratorSupportTest

**base**:

Executed above tests for 50 iterations on windows and Mac.
No regressions observed.All tests run fine.

-------------

Commit messages:
 - Remove deprecated call
 - Remove deprecated method runFinalization
 - Remove calls to deprecated method System.runFinalization

Changes: https://git.openjdk.java.net/jfx/pull/781/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=781&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278430
  Stats: 38 lines in 20 files changed: 0 ins; 38 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/781.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/781/head:pull/781

PR: https://git.openjdk.java.net/jfx/pull/781