Critical: Remove UserSecretsId and update package references to latest versions

## 🚨 Critical Updates Needed - Propagation from functions-quickstart-dotnet-azd PR #18

This issue tracks critical changes that need to be applied to maintain consistency across Azure Functions AZD templates, based on [PR #18](https://github.com/Azure-Samples/functions-quickstart-dotnet-azd/pull/18) merged on August 7, 2025.

### Required Changes

#### 1. 🔒 Remove UserSecretsId from .csproj
**Security Issue:** Templates should not include hardcoded UserSecretsId values.

```xml

09bd123b-3401-4507-b92c-0b283b95b537
```

#### 2. 📦 Update Package References to Latest Versions
Update all Azure Functions package references in .csproj files:

```xml

```

**Note:** This template may use additional SQL-specific packages that should also be updated to their latest versions.

#### 3. 🏗️ Remove Application Insights from Bicep Outputs
Remove this line from `infra/main.bicep`:

```bicep
// REMOVE this line
output APPLICATIONINSIGHTS_CONNECTION_STRING string = monitoring.outputs.name
```

### Impact
- **Security:** Removes exposed secrets from template
- **Compatibility:** Updates to latest stable versions
- **Consistency:** Aligns with current best practices across all Azure Functions AZD templates

### Reference
- **Source PR:** https://github.com/Azure-Samples/functions-quickstart-dotnet-azd/pull/18
- **Author:** @nzthiago
- **Scope:** Part of batch propagation across 19 Azure Functions AZD templates

### Related Templates
This same issue applies to:
- functions-quickstart-dotnet-azd-timer ✅ [Issue #7](https://github.com/Azure-Samples/functions-quickstart-dotnet-azd-timer/issues/7)
- functions-quickstart-dotnet-azd-cosmosdb ✅ [Issue #4](https://github.com/Azure-Samples/functions-quickstart-dotnet-azd-cosmosdb/issues/4)
- functions-quickstart-dotnet-azd-eventgrid-blob
- durable-functions-quickstart-dotnet-azd

/cc @nzthiago

Vergleiche die .csproj-Dateien des Repositorys und infra/main.bicep mit dem referenzierten functions-quickstart-dotnet-azd PR #18. Überprüfe alle Azure Functions- und SQL-spezifischen Paketverweise, entferne die angegebene UserSecretsId und die Application Insights-Ausgabe und verifiziere, dass die resultierenden Vorlagendateien den angeforderten Versionen und Einstellungen entsprechen.

Vom Indexierungsmodell aus dem Issue-Text verfasst.