shell32/tests: Don't leave behind open explorer windows.

[Marvin]

Hi,

While running your changed tests on Windows, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?
Full results can be found at
https://testbot.winehq.org/JobDetails.pl?Key=14594

Your paranoid android.


=== w2003std (32 bit progman_dde) ===
progman_dde.c:377: Test failed: Window "C:\Documents and Settings\All Users\Start Menu\Programs\Group1" was not created in 45 seconds - assumed failure.  [S_G:12]

=== w7u (32 bit progman_dde) ===
progman_dde.c:519: Test failed: DeleteGroup Group1: Expected Error DMLERR_NO_ERROR, received DMLERR_EXECACKTIMEOUT.  [D_G:13]

=== wvistau64 (64 bit progman_dde) ===
progman_dde.c:571: Test failed: DeleteItem f2g1Name.lnk: Expected Error DMLERR_NO_ERROR, received DMLERR_EXECACKTIMEOUT.  [D_I:5]