[BUG] Creating a Slot Incorrectly Truncates AppService Name when Creating Hostname

[Exile322]

Library name and version

Azure.ResourceManager.AppService 1.4.0

Describe the bug

When programmatically creating a Deployment Slot for an AppService in C#, the Hostname of the slot always reserves 19 characters even if the actual slot name isn't that long. When using Unique Hostnames this means there's only 23 characters available for the appservice name part which is automatically truncated when creating the slot. When using the same names to create the slot in the portal it does not reserve 19 characters or truncate the appservice name.

Expected behavior

AppService Name: testing-abcdefghijklmnopqrstuvwxyz1
Slot Name: staging
Unique Hostnames Enabled

Expected Hostname: testing-abcdefghijklmnopqrstuvwxyz1-staging-<16 char hash>

Actual behavior

Actual Hostname created: testing-abcdefghijklmno-staging-<16 char hash>

Reproduction Steps

1. Create AppService called testing-abcdefghijklmnopqrstuvwxyz1 with unique hostnames enabled (I had subscription level reuse)
2. Create Slot called staging
3. View the hostname of the slot in the portal and observe the truncated appservice name part and a length of 48 characters instead of the 60 character limit

Environment

No response