Apple Business rename: Copy tweak and URL change (#44829)

- Add redirect for old /abm URL


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Updates**
* Updated Apple Business Manager integration URL paths for consistency.
* Refined UI messaging and guide text in the Apple Business Manager
setup flow.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>

frontend/pages/admin/IntegrationsPage/cards/MdmSettings/AppleBusinessManagerPage/AppleBusinessManagerPage.tsx

@@ -156,7 +156,7 @@ const AppleBusinessManagerPage = ({ router }: { router: InjectedRouter }) => {
       return (
         <EmptyState
           header="Turn on Apple MDM"
-          info="To add your ABM and enable automatic enrollment for macOS, iOS, and iPadOS hosts, first turn on Apple MDM."
+          info="To add your AB and enable automatic enrollment for macOS, iOS, and iPadOS hosts, first turn on Apple MDM."
           primaryButton={
             <Button onClick={() => router.push(PATHS.ADMIN_INTEGRATIONS_MDM)}>
               Turn on

frontend/pages/admin/IntegrationsPage/cards/MdmSettings/AppleBusinessManagerPage/components/AddAbmModal/AddAbmModal.tsx

@@ -53,8 +53,7 @@ const AddAbmModal = ({ onCancel, onAdded }: IAddAbmModalProps) => {
   return (
     <Modal className={baseClass} title="Add AB" onExit={onCancel} width="large">
       <p>
-        Follow the step-by-step guide to connect Fleet to Apple Business
-        Manager.{" "}
+        Follow the step-by-step guide to connect Fleet to Apple Business.{" "}
         <CustomLink
           url="https://fleetdm.com/learn-more-about/setup-abm"
           text="Learn how"