OB gave no chat log indication it was landing b/c walked into OB radius

## Testmerges
#10999: 'Fix of various plane related issues' by Blundir at commit f85a7153c4
#10908: 'Adds additional checks to pouncing up a z level' by Git-Nivrak at commit 040e0c0f87
#10925: 'Cape River Mining Colony - Ground Map' by Steelpoint at commit 9e2e0a49ba
#11170: '[WIP] Yautja Survivor' by realforest2001 at commit c19444221b
#10623: 'A.S.S - Assault, Support, Security' by Git-Nivrak at commit 32ce9551ef
#11389: 'Yautja Leap' by realforest2001 at commit 04eaaf0dae
#11414: '[WIP] Predship Multi-Z' by realforest2001 at commit 6a2024c6ff
#11420: 'Yautja Visuals Import' by realforest2001 at commit ffe3de37d6

## Round ID
31688

## Description of the bug
My chat log for this round shows zero OB mentions yet I was hit by OB

Was fighting south, far enough to not see the OB alerts. Ran North and heard the OB landing sound faintly but no chat log messages. Then a cluster shell landed directly on me and SADAR gibbing him.

Just the quiet sound cue is very misleading as typically if you do not see the chat display you are far enough from the impact for CAS, mortar and OB normally

## What's the difference with what should have happened?
A Chat display and not just the quiet sound cue would play as I got close.

## How do we reproduce this bug?
stand far away from OB to receive no notification
Walk into OB area after chat messages stop being displayed

## Attached logs
```
N/A
```

## Additional details
- Author: Paperbirch
- Admin: Forest2001
- Note: None

No source file, test, or entry point is identified. Reproduce the round 31688 scenario by staying outside the OB notification area, then walking into it after alerts stop; done means entering the area produces a chat indication as well as the landing sound, rather than only the quiet cue.

Written by the indexing model from the issue text.