Bug 22054: Updated the error message for attempting to renew an onsite checkout

Bug 22054: Updated the error message for attempting to renew an onsite checkout

To test:

1) Enable OnSiteCheckouts system preference
2) Checkout an item checking the onsite checkout checkbos in more
options
3) Go to circulation > pending on-site checkouts
4) Verify the checkout shows
5) Go to circulation > renew
6) Try to renew the on-site checkout using the barcode
7) Verify display:

onsite_checkout  Continue without renewing

8) apply the patch and reload page with error message
9) verify display:

Item cannot be renewed because it's an onsite checkout

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>