Prune Media Job delays app startup

[himeshr]

Describe the bug
Issue reported as part of Urgent ticket
In any organisation, where there are media FormElements, as we keep downloading or uploading media content through Avni app, we'll grow the number of media items that have to be checked for expiry. For each of this media items, we check across all entities mediaObservation fields for match, this takes a large amount of time for even relatively small number of synced entities. As Background jobs run on every app start up, the user faces this issue every time he opens app.

For user with N synced entities and M media items, we can potentially end up performing N * M search at every App start-up, ruining User's App Launch experience.

To Reproduce
Steps to reproduce the behavior:
Using any version of Avni APK

1. Login as any user for goonj
2. Perform sync
3. Navigate to Activities list page and randomly download media-items
4. Restart the app
5. Observe that app splash screen stays on for longer and longer duration of time as we download more media-items

Expected behavior
The download of more and more media-items shouldnot exponentially increase the app launch time.

Screenshots
Refer ticket, noordeen user recording

Technical inputs

• Ensure the PruneMedia Job is not run on every app launch, but rather only once a week or even once a month
• Ensure Order of Growth for PruneMedia job is better than O(N^2), which is the case now

Smartphone (please complete the following information):

• Device: Any
• Version 10.1.0 and earlier

Developer Checklist
Developer fixing the bug should fill this checklist.

• Does the fix require extensive regression testing?
• Are you mentioning the required scenarios that could be affected?

Discussion points:

• Show a progress bar with message to let know user what is happening - this need to be made once in
• Why cant we delete it once sync is done? ie., once the replacement of observations is done? that is in post Sync - this will save us from the need of traversing all the observations.

Standup discussion inputs

• We do not have instances where the job effectively deletes media, as the catchment doesn't change in general then the entities will remain pointing to the media content, rendering the prune job ineffective
• We should also think of making this a User triggered operation than Automatic Background job

[himeshr]

Vivek's input for this card was to not optimize this job and remove it permanently, in-line with Joy's input on the lack of need for such a job for Majority of the Users..