applets/weather: fix crash when destroying IonControl

BUG: 514200

Before	After
Screencast_20260129_023933	Screencast_20260129_023816

The trace is similar:

Trace

                Stack trace of thread 40224:
                #0  0x00007ffaf12aa0fb pthread_kill (libc.so.6 + 0xaa0fb)
                #1  0x00007ffaf12447c8 raise (libc.so.6 + 0x447c8)
                #2  0x00007ffaf4f436c5 _ZN6KCrash19defaultCrashHandlerEi (libKF6Crash.so.6 + 0x56c5)
                #3  0x00007ffaf1244900 n/a (libc.so.6 + 0x44900)
                #4  0x00007ffaf1c9a9d0 _ZNK7QThread9isRunningEv (libQt6Core.so.6 + 0x29a9d0)
                #5  0x00007ffaca00aae3 _ZN10IonControl11checkQueuesEv (org.kde.plasma.weather.so + 0x68ae3)
                #6  0x00007ffaf1be00e2 n/a (libQt6Core.so.6 + 0x1e00e2)
                #7  0x00007ffaf1d608c4 _ZN18QFutureWatcherBase5eventEP6QEvent (libQt6Core.so.6 + 0x3608c4)
                #8  0x00007ffaf4303b70 _ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent (libQt6Widgets.so.6 + 0x103b70)
                #9  0x00007ffaf1b79158 _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt6Core.so.6 + 0x179158)
                #10 0x00007ffaf1b7aab0 _ZN23QCoreApplicationPrivate16sendPostedEventsEP7QObjectiP11QThreadData (libQt6Core.so.6 + 0x17aab0)
                #11 0x00007ffaf1e71698 n/a (libQt6Core.so.6 + 0x471698)
                #12 0x00007ffaf02ef429 n/a (libglib-2.0.so.0 + 0x68429)
                #13 0x00007ffaf02f0848 n/a (libglib-2.0.so.0 + 0x69848)
                #14 0x00007ffaf02f0982 g_main_context_iteration (libglib-2.0.so.0 + 0x69982)
                #15 0x00007ffaf1e6e9f2 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt6Core.so.6 + 0x46e9f2)
                #16 0x00007ffaf1b87306 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt6Core.so.6 + 0x187306)
                #17 0x00007ffaf1b7daf1 _ZN16QCoreApplication4execEv (libQt6Core.so.6 + 0x17daf1)
                #18 0x0000562efdcad345 main (/home/bogdan/kde/usr/bin/plasmashell + 0x34345)
                #19 0x00007ffaf1227b8b n/a (libc.so.6 + 0x27b8b)
                #20 0x00007ffaf1227c4b __libc_start_main (libc.so.6 + 0x27c4b)
                #21 0x0000562efdcad595 _start (/home/bogdan/kde/usr/bin/plasmashell + 0x34595)