delete_assignment: Resets the filter upon execution

[nus-pe-bot]

After deleting an assignment, the find filter is reset. I think this could be residual code from copying from delete_student so I am classifying it as a functionality bug.

Steps to reproduce (starting from a fresh install):

1. Create an assignment: add_assignment si/1 an/Test Assignment ms/100
2. Filter the first person: find Alex
3. Delete the assignment: delete_assignment si/1 ai/1
4. Note that the find filter is reset

After step 2:

After step 3 (Actual):

After step 3 (Expected): Note that the command output should be the same as the screenshot above. Other than that, the screenshot below is accurate.

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_{[original: nus-cs2103-AY2425S1/pe-interim#291] [original labels: severity.Medium type.FunctionalityBug]}

[emmannyyy]

Team's Response

This is essentially a duplicate, where the find filter is intentionally reset after each command.

It was intentional behaviour as we believe that users would want to see the main student list after executing each command.

Duplicate status (if any):

Duplicate of #1656