Fixes #29959, Apply without init error message

When going from a local backend to Terraform Cloud, if you skip the
`terraform init` and run `terraform apply` this will give the user more
clear instructions.

internal/command/meta_backend.go

@@ -1513,7 +1513,8 @@ configuration or state have been made.
 const errBackendInitCloudMigration = `
 Reason: %s.
 
-Migrating to Terraform Cloud requires reinitialization, to discover which Terraform Cloud workspaces belong to this configuration and to optionally migrate existing state to the corresponding Terraform Cloud workspaces.
+Changes to the Terraform Cloud configuration block require reinitialization,
+to discover any changes to the available workspaces.
 
 To re-initialize, run:
   terraform init