Add setting for default queue in admission controller

If the queue name is not defined during the job submission, YuniKorn admission controller will add a default queue to the pod labels.

When provided placement rule is defined, along with other placement rules, it is possible that only provided placement rule is executed and no other rule is exercised.

In the following scenario, when there are 3 placement rules defined,
placementrules:
        - name: provided
        - name: tag
        - name: fixed

The applications will be placed in the right queue, following the provided rule if the queue is defined during job submission. If the queue is not defined during job submission, admission controller will add a default queue name. This will again trigger the provided rule as the queue name will be found in the pod labels during placement rules execution. As a result, tag and fixed rules will never be executed and all the apps that do not have a queue defined will end up getting placed in the default queue.

To solve this, we should have a toggle in the admission controller configs whether to add the default queue to or not. Whenever such placement rules are setup, admission controller should be configured to skip adding the default queue name.