Android: Simplify deploy step widget setup

Remove the nested QGroupBox, inline code into only callers, etc.
Also use better display name for deploy step widget.

Change-Id: I579810c04dea032a98ba28db6de035048f801f75
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/plugins/android/android.pro

@@ -35,7 +35,6 @@ HEADERS += \
     androiddevicedialog.h \
     androiddeployqtstep.h \
     certificatesmodel.h \
-    androiddeployqtwidget.h \
     androidpotentialkit.h \
     androidsignaloperation.h \
     javaeditor.h \
@@ -84,7 +83,6 @@ SOURCES += \
     androiddevicedialog.cpp \
     androiddeployqtstep.cpp \
     certificatesmodel.cpp \
-    androiddeployqtwidget.cpp \
     androidpotentialkit.cpp \
     androidsignaloperation.cpp \
     javaeditor.cpp \
@@ -109,7 +107,6 @@ FORMS += \
     addnewavddialog.ui \
     androidcreatekeystorecertificate.ui \
     androiddevicedialog.ui \
-    androiddeployqtwidget.ui \
     androidbuildapkwidget.ui \
     adbcommandswidget.ui \
     androidsdkmanagerwidget.ui