LDAP group names are not lowercased when being deleted

[gnugnug]

Describe the bug
When creating, updating or reading LDAP groups, the group names are converted to lowercase. However this is not true when deleting a group. This leads to a situation where "vault write auth/ldap/MyGroup1" creates a group, but "vault delete auth/ldap/MyGroup1" does not delete it anymore. You have to use "vault delete auth/ldap/mygroup1" instead.

To Reproduce
Steps to reproduce the behavior:

1. $ vault server -dev
   ==> Vault server configuration:
   Administrative Namespace:
   Api Address: http://127.0.0.1:8200
   Cgo: disabled
   Cluster Address: https://127.0.0.1:8201
   Environment Variables: DBUS_SESSION_BUS_ADDRESS, HOME, HOSTTYPE, LANG, LESSCLOSE, LESSOPEN, LOGNAME, LS_COLORS, NAME, OLDPWD, PATH, PWD, SHELL, SHLVL, TERM, USER, WSLENV, WSL_DISTRO_NAME, _
   Go Version: go1.23.3
   Listener 1: tcp (addr: "127.0.0.1:8200", cluster address: "127.0.0.1:8201", disable_request_limiter: "false", max_request_duration: "1m30s", max_request_size: "33554432", tls: "disabled")
   Log Level:
   Mlock: supported: true, enabled: false
   Recovery Mode: false
   Storage: inmem
   Version: Vault v1.18.3, built 2024-12-16T14:00:53Z

2. $ vault auth enable ldap
   Success! Enabled ldap auth method at: ldap/

3. $ vault write auth/ldap/groups/Test policies=123
   Success! Data written to: auth/ldap/groups/Test

4. $ vault read auth/ldap/groups/Test
   Key Value
   policies [123]

5. $ vault read auth/ldap/groups/test
   Key Value
   policies [123]

6. $ vault delete auth/ldap/groups/Test
   Success! Data deleted (if it existed) at: auth/ldap/groups/Test

7. $ vault read auth/ldap/groups/Test
   Key Value
   policies [123]

8. $ vault read auth/ldap/groups/test
   Key Value
   policies [123]

9. $ vault delete auth/ldap/groups/test
   Success! Data deleted (if it existed) at: auth/ldap/groups/test

10. $ vault read auth/ldap/groups/Test
    No value found at auth/ldap/groups/Test

11. $ vault read auth/ldap/groups/test
    No value found at auth/ldap/groups/test

Expected behavior
I would expect that step 6. above deletes the group, the same way it was created, and that the commands in step 7. an 8. return "No value found".