Update meeting scheduling button text for clarity

Correct the text for the "Add meeting" button in both Arabic and English locale files to remove unnecessary characters.

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artifacts/tx-os/src/locales/ar.json

@@ -826,7 +826,7 @@
     "dragRow": "اسحب لإعادة الترتيب",
     "editMeetingTitle": "تعديل عنوان الاجتماع",
     "schedule": {
-      "addRow": "+ أضف اجتماعًا جديدًا",
+      "addRow": "أضف اجتماع جديد",
       "newMeetingDefaultAr": "اجتماع جديد",
       "newMeetingDefaultEn": "New meeting",
       "timeStart": "وقت البداية",

artifacts/tx-os/src/locales/en.json

@@ -775,7 +775,7 @@
       "unmerge": "Unmerge"
     },
     "schedule": {
-      "addRow": "+ Add meeting",
+      "addRow": "Add meeting",
       "newMeetingDefaultAr": "اجتماع جديد",
       "newMeetingDefaultEn": "New meeting",
       "timeStart": "Start time",