Scope policy job options under a single key

What does this MR do and why?

Scope policy job options under a single policy key and simplify the naming. Since we add the policy key only for policy jobs, the option execution_policy_job: true becomes superfluous and can be removed.

Old:

{
  "execution_policy_job": true,
  "execution_policy_name": "My policy",
  "execution_policy_pre_succeeds": true,
  "execution_policy_variables_override": { "allowed": false }
}

New:

{
  "policy": {
    "name": "My policy",
    "pre_succeeds": true,
    "variables_override": { "allowed": false }
  }
}

References

• !190625 (diffs, comment 2820300646)

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Related to #459001