When multiblocks is disabled if an admin tries to block an IP that is already blocked by a range block, form is never shown
**Steps to reproduce:**
- Create a block on 127.0.0.1/16
- Try to create a block on 127.0.0.20
- Form is still hidden
**Derived Requirement**
Ensure that when MultiBlocks is disabled, admins are able to view and interact with the Special:Block form when attempting to block a single IP address that falls within an already blocked IP range.
====Test Steps
__Test Case 1: Ensure form is visible when blocking an IP within an existing blocked range with MultiBlocks disabled__
1. Disable MultiBlocks (`$wgEnableMultiBlocks = false`) on the wiki.
2. Log in as an admin user with permission to block users.
3. Navigate to Special:Block.
4. Block the IP range '127.0.0.1/16'.
5. After the block is created, attempt to block the individual IP '127.0.0.20'.
6. ✅❓❌⬜ **AC1:** Confirm that the Special:Block form displays correctly and allows setting a new block on '127.0.0.20'.
__Test Case 2: Verify correct behavior when blocking an IP within an existing blocked range with MultiBlocks enabled__
1. Enable MultiBlocks (`$wgEnableMultiBlocks = true`) on the wiki.
2. Log in as an admin user with permission to block users.
3. Navigate to Special:Block.
4. Block the IP range '127.0.0.1/16'.
5. After creating the blo, attempt to block the individual IP '127.0.0.20'.
6. ✅❓❌⬜ **AC2:** Confirm that the Special:Block form displays correctly, allowing the admin to create an overlapping block on '127.0.0.20' without errors.
== QA Results - Local
| **AC** | **Status** | **Details** |
| ----- | ----- | ----- |
| 1 | ✅|T392049#10777595
| 2 | ✅|T392049#10777595