fix: use correct names for autoscaler policies configuration (#1167)

## Description

PascalCase was used to create the `[[runners.autoscaler.policy]]` which
is wrong according to the documentation. This PR fixes the names in the
configuration file. `IdleCount` --> `idle_count`

The worker instances were used once and then terminated. This resulted
in a high load of some AWS autoscaling APIs and we got rate limiting. In
the end most pipelines failed.

## Verification

Deployed the changes into my environment. The worker machines are reused
now.

Author: kayman-mk

main.tf

@@ -130,7 +130,7 @@ locals {
       runners_autoscaling = [for config in var.runner_worker_docker_autoscaler_autoscaling_options : {
         for key, value in config :
         # Convert key from snake_case to PascalCase which is the casing for this section.
-        join("", [for subkey in split("_", key) : title(subkey)]) => jsonencode(value) if value != null
+        key => jsonencode(value) if value != null
       }]
   })