Fleet UI: Remove incorrect copy (#42586)

## Issue
Closes #40683 

## Description
- Removed from 2 modals that were rendering it

## Testing

- [x] Added/updated automated tests
- [x] QA'd all new/changed functionality manually

frontend/components/ActivityDetails/InstallDetails/SoftwareInstallDetailsModal/SoftwareInstallDetailsModal.tsx

@@ -285,7 +285,7 @@ export const SoftwareInstallDetailsModal = ({
     if (hostSoftware?.installed_versions?.length) {
       return <InventoryVersions hostSoftware={hostSoftware} />;
     }
-    return "If you uninstalled it outside of Fleet it will still show as installed.";
+    return null;
   };
 
   const renderInstallDetailsSection = () => {

frontend/components/ActivityDetails/InstallDetails/SoftwareIpaInstallDetailsModal/SoftwareIpaInstallDetailsModal.tsx

@@ -391,7 +391,7 @@ export const SoftwareIpaInstallDetailsModal = ({
     if (hostSoftware?.installed_versions?.length) {
       return <InventoryVersions hostSoftware={hostSoftware} />;
     }
-    return "If you uninstalled it outside of Fleet it will still show as installed.";
+    return null;
   };
 
   const renderInstallDetailsSection = () => {

frontend/components/ActivityDetails/InstallDetails/VppInstallDetailsModal/VppInstallDetailsModal.tests.tsx

@@ -562,53 +562,4 @@ describe("VPP Install Details Modal", () => {
       )
     ).toBeInTheDocument();
   });
-
-  it("does not render the stale uninstall sentence on My device", async () => {
-    mockServer.use(getDeviceVppCommandResultHandler);
-
-    const hostSoftware = createMockHostSoftware({
-      id: 123,
-      status: "installed",
-      name: "Keynote",
-      display_name: "Keynote",
-      installed_versions: [],
-      source: "apps",
-      app_store_app: createMockHostAppStoreApp({
-        platform: "darwin",
-        last_install: {
-          command_uuid: "acknowledged-uuid",
-          installed_at: "2025-08-10T12:00:00Z",
-        },
-      }),
-    });
-
-    renderWithBackend(
-      <VppInstallDetailsModal
-        details={{
-          fleetInstallStatus: "installed",
-          hostDisplayName: "Marko's MacBook Pro",
-          appName: "Keynote",
-          commandUuid: "acknowledged-uuid",
-          platform: "darwin",
-        }}
-        deviceAuthToken="device-token"
-        hostSoftware={hostSoftware}
-        onCancel={jest.fn()}
-      />
-    );
-
-    // Wait for the success state to render
-    await waitFor(() => {
-      // Just assert on the actual text we render in this mode
-      expect(screen.getByText(/Keynote/i)).toBeInTheDocument();
-      expect(screen.getByText(/is installed\./i)).toBeInTheDocument();
-    });
-
-    // And still assert that the “stale uninstall” copy is omitted
-    expect(
-      screen.queryByText(
-        /If you uninstalled it outside of Fleet it will still show as installed/i
-      )
-    ).not.toBeInTheDocument();
-  });
 });