Avoid drawing the launcher pill outside the view bounds

When drawing the launcher pill, the round rect corners may extend a little
beyond the view bounds.  Add a small padding for the round rect corners around
the text view to avoid drawing out of bounds for the view.

Bug: 341217082
Flag: com.android.launcher3.enable_contrast_tiles
Test: Manual, visual change
Change-Id: I41cd2ad9909081cb66751d7f03e52f03f8ae928b