github-zephyrproject-rtos: Remove HCP Vault data source

This commit removes the unused HCP Vault data source.

The GitHub token for invoking GitHub APIs is expected to be provided
using the `GITHUB_TOKEN` environment variable, both when executing
locally and remotely in the HCP Cloud.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

terraform/github-zephyrproject-rtos/main.tf

@@ -1,8 +1,3 @@
-# HashiCorp Vault Secrets zephyr-secrets Vault
-data "hcp_vault_secrets_app" "zephyr_secrets" {
-  app_name = "zephyr-secrets"
-}
-
 # GitHub provider
 provider "github" {
   owner = "zephyrproject-rtos"