Migrate GitHub (Webhooks) V2 connector Function to Flex Consumption plan

**Is your feature request related to a problem? Please describe.**
The GitHub (using Webhooks) V2 data connector deploys its Azure Function on the Linux Consumption plan, which Microsoft is retiring on September 30, 2028. Microsoft no longer ships feature or language enhancements to this plan and directs customers to migrate to Flex Consumption. This means the connector currently onboards customers onto a deprecating platform, and each customer will eventually face a manual, time-pressured migration before the retirement date. The Consumption plan also can't integrate with a virtual network, so the Function App can't reach Storage or Key Vault restricted to private endpoints, blocking "no public network access" environments.

**Describe the solution you'd like**
Update the GitHub (using Webhooks) V2 connector deployment templates (ARM/Bicep) to deploy the Function App on the Flex Consumption plan instead of Consumption.

**Describe alternatives you've considered**

- Manual per-customer migration: Each customer redeploys or migrates the Function to Flex Consumption themselves before the 2028 retirement. This is error-prone, duplicates effort, and leaves customers on an unsupported plan in the interim.
- Premium: Also supports VNet integration, but loses the serverless scale-to-zero cost model that Flex Consumption preserves, making it a costlier default.
- Keeping the Consumption plan: Not viable long term given the confirmed retirement date and the lack of VNet support.

**Additional context**

- [Migrate Consumption plan apps to Flex Consumption](https://learn.microsoft.com/azure/azure-functions/migration/migrate-plan-consumption-to-flex)
- [Azure Functions networking options (VNet support by plan)](https://learn.microsoft.com/azure/azure-functions/functions-networking-options)