[#12048] Migrate InstructorNotificationsPageE2E

[yuanxi1]

Part of #12048

Outline of Solution

1. Migrate InstructorNotificationsPageE2E test to use sql entities
2. Encountered an error when loading the sql data bundle. In particular, Hibernate fails to persist Instructor entity as the Course entity it refers to is not in managed state by Hibernate (some info on entity state transition)

From this stackoverflow post, possible cause is the unidirectional @ManyToOne relation on User but no @OneToMany with CascadeType.ALL on the Course side.

Adding @OneToMany + CascadeType.ALL in Course can fix the error, however since one course usually has many users, this may lead to slower performance.

As mentioned in the same post, one fix without adding @OneToMany + CascadeType.ALL is to explicitly set the parent in child after parent is created, which is adopted as a temporary fix in this pr.

[github-actions]

Hi @yuanxi1, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Title must start with the issue number the PR is fixing in square brackets, e.g. [#<issue-number>]
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[weiquu]

Hi @yuanxi1, thanks for the research! I think the temp fix is fine - we'll probably try to resolve this when refactoring entities. Could you add the test to the .xml file so that it runs on github actions? Can take a look at the tele message for more details

edit: sorry pls ignore the first comment haha - refer to what u discussed with cedric

[cedricongjh]

LGTM, thanks for the work and investigating the issue with persisting the databundle!

[weiquu]

LGTM!