fix: update mongodb fcv to 6 (#41534)

## Description

Looks like when the embedded MongoDB version was last updated, the
feature compatibility version parameter was not updated. This means that
any instances that started on 1.66 or less using the embedded MongoDB
didn't have their compatibility version updated. This'll make the jump
to 7.x harder as we need to ensure this is at least 6 in those
scenarios. Getting this in place now.

Fixes #`Issue Number`  
_or_  
Fixes `Issue URL`
> [!WARNING]  
> _If no issue exists, please create an issue first, and check with the
maintainers if the issue is valid._

## Automation

/ok-to-test tags=""

### 🔍 Cypress test results
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> If you modify the content in this section, you are likely to disrupt
the CI result for your PR.

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## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [x] No


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Chores**
* Updated MongoDB feature compatibility from version 5.x to 6.x in
deployment configuration.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: wyattwalter

deploy/docker/fs/opt/appsmith/mongodb-fixer.sh

@@ -17,10 +17,10 @@ tlog "MongoDB is RUNNING"
 
 for _ in {1..60}; do
   if mongosh --quiet "$APPSMITH_DB_URL" --eval '
-    parseFloat(db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1}).featureCompatibilityVersion.version) < 5 &&
-      db.adminCommand({setFeatureCompatibilityVersion: "5.0"})
+    parseFloat(db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1}).featureCompatibilityVersion.version) < 6 &&
+      db.adminCommand({setFeatureCompatibilityVersion: "6.0"})
   '; then
-    tlog "MongoDB version set to 5.0"
+    tlog "MongoDB version set to 6.0"
     break
   fi
   sleep 1