[SCHEMA] Migrate Discharge Reason to Integer Format

[Ashesh3]

Frontend PR: ohcnetwork/care_fe#6807

Proposed Changes

This PR introduces a fundamental change in the representation of the discharge reason field, transitioning from a string-based approach to an enum-based integer format. This modification impacts multiple files including serializers and models, ensuring consistency and improved data handling across the system. Key changes include the introduction of the DiseaseReasonEnum class and updates to the discharge_reason field in various models to reflect the new enum-based approach. This refactor not only streamlines data processing but also aligns with best practices in data representation, thereby enhancing the system's overall efficiency and maintainability.

Associated Issue

• Convert discharge_reason to IntegerField #1739

@coronasafe/care-backend-maintainers @coronasafe/care-backend-admins

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e09e4c1) 61.36% compared to head (cfcdff2) 61.38%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1749      +/-   ##
==========================================
+ Coverage   61.36%   61.38%   +0.02%     
==========================================
  Files         211      211              
  Lines       11587    11595       +8     
  Branches     1659     1660       +1     
==========================================
+ Hits         7110     7118       +8     
  Misses       4205     4205              
  Partials      272      272              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Ashesh3]

As per discussion, this change will be done in 3 steps:

• Schema Changes
• Migrating Data
• Moving the temp field back to the original field and deprecate the temp field.

I've converted this PR to just the schema change.