fix: perps not reconnecting on account switch (MetaMask#22068)

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## **Description**

This PR introduces a change that keeps the Perps redux subscription
active throughout the app lifecycle. This ensures that things like
`reconnectWithNewContext()` gets triggered automatically when things
like account switches get called. We were noticing that this
reconnection was regressing on some
[PerpsTab](MetaMask#22044)
refactoring for full page scroll, so this should help mitigate this type
of regression.

I don't think this will introduce any major performance regression. The
Redux subscription is pretty lightweight, and I think we can keep it
alive throughout the app lifecycle. Worth reviewing with @abretonc7s
here though.

## **Changelog**

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CHANGELOG entry: Maintain Perps redux state monitoring throughout app
lifecycle

## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

## **Screenshots/Recordings**

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### **Before**

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### **After**

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## **Pre-merge author checklist**

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Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
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## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Keeps Perps Redux monitoring active by eliminating
`cleanupStateMonitoring()` during disconnect/grace paths and only
cleaning preloaded subscriptions.
> 
> - **PerpsConnectionManager
(`app/components/UI/Perps/services/PerpsConnectionManager.ts`)**:
>   - **Disconnection flow**:
> - Remove calls to `cleanupStateMonitoring()` during
actual/grace-period disconnection.
> - Keep Redux monitoring active even when disconnecting or not
connected.
> - Continue cleaning only preloaded subscriptions via
`cleanupPreloadedSubscriptions()`.
>   - **Grace period handling**:
> - Drop redundant else-branches that previously cleaned up monitoring
when not connected.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
7b92699. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: gambinish

app/components/UI/Perps/services/PerpsConnectionManager.ts

@@ -260,9 +260,6 @@ class PerpsConnectionManagerClass {
             // Clean up preloaded subscriptions
             this.cleanupPreloadedSubscriptions();
 
-            // Clean up state monitoring when leaving Perps
-            this.cleanupStateMonitoring();
-
             // Reset state before disconnecting to prevent race conditions
             this.isConnected = false;
             this.isInitialized = false;
@@ -286,9 +283,6 @@ class PerpsConnectionManagerClass {
         })();
 
         await this.disconnectPromise;
-      } else {
-        // Even if not connected, clean up monitoring when leaving Perps
-        this.cleanupStateMonitoring();
       }
     } else {
       DevLogger.log(
@@ -819,9 +813,6 @@ class PerpsConnectionManagerClass {
           'PerpsConnectionManager: Starting grace period before disconnection',
         );
         this.scheduleGracePeriodDisconnection();
-      } else {
-        // Even if not connected, clean up monitoring when leaving Perps
-        this.cleanupStateMonitoring();
       }
     }
   }