This was originally present to prevent multiple evaluations of
the same items when using GDB/MI varobjs. This also prevented
a proper update of child item count. Until recently this did
not negatively affect the GUI due to excessive use of reset()
in the view. This has changed, so the missing update was visible now,
solved here by removing the cache, which is not needed anyways,
since we don't use varobjs anymore.

Task-number: QTCREATORBUG-14705
Change-Id: I3bbcd0525f02c10765f20be3a55708835747b307
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>