Fleet UI: Fix TS errors from removed button variants (#49828)

frontend/components/FleetsDropdown/FleetsDropdown.tsx

@@ -209,15 +209,10 @@ const CustomMenu = (props: MenuProps<INumberDropdownOption, false>) => {
           onMouseDown={addFleetMouseDown}
           onKeyDown={addFleetKeyDown}
         >
-          <Button
-            variant="brand-inverse-icon"
-            onClick={onClickAddFleet}
-            iconStroke
-            size="small"
-          >
+          <Button variant="subdued" onClick={onClickAddFleet} size="small">
             <>
               Add fleet
-              <Icon name="plus" color="core-fleet-green" />
+              <Icon name="plus" />
             </>
           </Button>
         </div>

frontend/pages/hosts/details/HostDetailsPage/components/ReleaseFromABModal/ReleaseFromABModal.tsx

@@ -113,7 +113,7 @@ const ReleaseFromABModal = ({
       <ModalFooter
         primaryButtons={
           <>
-            <Button variant="inverse-alert" onClick={onModalExit}>
+            <Button variant="secondary" onClick={onModalExit}>
               Cancel
             </Button>
             <Button