cui: unused code in SvxAreaTabPage::ClickGradientHdl_Impl

This is unused since commit 5627d0bdaf1385df9d90dcec3a319c82c089c2ca
(Fix #86988#: Redesign of dialogs, 2001-05-15), and just getting rid of it
avoids a crash on Insert -> Frame -> Area -> Gradient in Writer.

Copy&paste of problematic code, take 2.

Change-Id: I5be2b0b3280826d50ea196f95f8ac92d7856ae7d
cui: unused code in SvxAreaTabPage::ClickBitmapHdl_Impl

This is unused since commit 5627d0bdaf1385df9d90dcec3a319c82c089c2ca
(Fix #86988#: Redesign of dialogs, 2001-05-15), and just getting rid of
it avoids a crash on Insert -> Frame -> Area -> Bitmap in Writer.

Copy&paste of problematic code, take 3.

Change-Id: Ide488585bbc6aed157fa6058bcfd1cd0a6d2c7aa