rpm-ostree: Update unit tests for rw karg

See parent commit.

See: https://fedoraproject.org/wiki/Changes/Silverblue_Kinoite_readonly_sysroot
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2086489

tests/unit_tests/pyanaconda_tests/modules/payloads/payload/test_rpm_ostree_tasks.py

@@ -540,7 +540,7 @@ def test_btrfs_run(self, devdata_mock, storage_mock, symlink_mock, rename_mock,
             exec_mock.assert_called_once_with(
                 "ostree",
                 ["admin", "instutil", "set-kargs", "BOOTLOADER-ARGS", "root=FSTAB-SPEC",
-                 "rootflags=subvol=device-name"],
+                 "rootflags=subvol=device-name", "rw"],
                 root=sysroot
             )
 
@@ -576,7 +576,7 @@ def test_nonbtrfs_run(self, devdata_mock, storage_mock, symlink_mock, rename_moc
             )
             exec_mock.assert_called_once_with(
                 "ostree",
-                ["admin", "instutil", "set-kargs", "BOOTLOADER-ARGS", "root=FSTAB-SPEC"],
+                ["admin", "instutil", "set-kargs", "BOOTLOADER-ARGS", "root=FSTAB-SPEC", "rw"],
                 root=sysroot
             )