fix/: fct_student_diploma sort_index hard-coded NULL casted to int

[smckee-tnedu]

Description & motivation

Databricks (or DBT?) assigns a data type of "void" to columns where every field is null. This breaks being able to do something simple like "select *" within databricks web ui (and other places). Casted this column to an int data type when it is hard coded to null.

Breaking changes introduced by this PR:

Should be none. But I cannot test in Snowflake.

PR Merge Priority:

• Low
• Medium
• High

Changes to existing files:

fct_student_diploma.sql: Casted NULL as sort_index to int so that databricks (or dbt?) doesn't flip out trying to show a void type

New files created:

None

Tests and QC done:

Tested locally in TN. select * on fct_student_diploma now doesn't throw crazy errors.

edu_wh PR Review Checklist:

Make sure the following have been completed before approving this PR:

• Description of changes has been added to Unreleased section of CHANGELOG.md. Add under ## New Features for features, etc.
• Code has been tested/checked for Databricks and Snowflake compatibility - EA engineers see Databricks checklist here
• Reviewer confirms the grain of all tables are unchanged, OR any changes are expected, communicated, and this PR is flagged as a breaking change (not for patch release)
• If a new configuration xwalk was added:
  • The code is written such that the xwalk is optional (preferred), and this behavior was tested, OR
  • The code is written such that the xwalk is required, and the required xwalk is added to edu_project_template, and this PR is flagged as breaking change (not for patch release)
  • A description for the new xwalk has been added to EDU documentation site here
• If a new configuration variable was added:
  • The code is written such that the variable is optional (preferred), and this behavior was tested, OR
  • The code is written such that the variable is required, and a default value was added to edu_project_template, and this PR is flagged as breaking change (not for patch release)
  • A description for the new variable has been added to EDU documentation site here

None