Fix destroyed cooldown structures reappearing in game (#3997)

## Description:
Stop deleted missile silos from reappearing after cooldown expiry

before

https://github.com/user-attachments/assets/714d3580-b60d-479e-8e45-6ee065b79d54

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:
aotumuri

src/core/execution/MissileSiloExecution.ts

@@ -18,6 +18,11 @@ export class MissileSiloExecution implements Execution {
       return;
     }
 
+    if (!this.silo.isActive()) {
+      this.active = false;
+      return;
+    }
+
     // frontTime is the time the earliest missile fired.
     const frontTime = this.silo.missileTimerQueue()[0];
     if (frontTime === undefined) {