fix programming evaluation polling

[adi-herwana-nus]

This PR fixes continued polling for autograding jobs on the programming submission edit page after the user navigates away (and double polling when they navigate back). Since the autograding job polling would only affect that page's UI, polling should only occur when the user is on that page.

Previous Behavior

Fetching submission details triggered a setInterval() timer (via pollJob() helper function) to poll the backend for ongoing autograding jobs. This timer was not cleared with clearInterval() when the user navigated away, resulting in the timer being effectively orphaned.
Clicking "Run Code" button also calls the pollJob() helper function, leading to the same behavior.

New Behavior

Fetching submission details no longer triggers polling automatically. Instead, polling is now managed by the SubmissionEditIndex React component:

• This component starts polling timers (one for live feedback and one for evaluation) on mount and clears it on unmount.
• The evaluation timer polls for autograding jobs in progress, which is determined by the question data in the Redux state.
• When the user clicks "Run Code," the Redux state is updated to start polling for that specific question.

Both operations no longer use pollJob() helper function. In the future, we might want to revisit whether we want to rewrite other occurrences of the function to avoid the orphan timer issue, or decide if there are some polling calls that should persist between pages.