qtdiag: Disable autotest for all cross-built platforms

Timeouts have been observed on
arm-little_endian-ilp32-eabi-hardfloat shared (dynamic).

Task-number: QTBUG-79580
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Liang Qi <liang.qi@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit ec310d3d

)
Change-Id: I6e6525c961e8b2611a8f5485175a42a83facd723
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

tests/auto/auto.pro

@@ -15,7 +15,7 @@ SUBDIRS=\
 installed_cmake.depends = cmake
 
 # These tests don't make sense for cross-compiled builds
-cross_compile:SUBDIRS -= linguist
+cross_compile:SUBDIRS -= linguist qtdiag
 
 # These tests need the QtHelp module
 !qtHaveModule(help): SUBDIRS -= \
@@ -26,5 +26,4 @@ cross_compile:SUBDIRS -= linguist
     qhelpprojectdata \
 
 !qtConfig(process): SUBDIRS -= qtattributionsscanner linguist qtdiag windeployqt
-android|qnx: SUBDIRS -= qtdiag
 !win32|winrt: SUBDIRS -= windeployqt