Adds a constant for the diag 'Deleting' state. Only used in other repos

[Pure-AdamuKaapan]

What this PR does / why we need it:
Will simply be used to replace a hardcoded string in other repos.

[github-actions]

This PR is stale because it has been in review for 3 days with no activity.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (de9416f) 75.85% compared to head (4abd941) 75.68%.

❗ Current head 4abd941 differs from pull request most recent head faeee28. Consider uploading reports for the commit faeee28 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1197      +/-   ##
==========================================
- Coverage   75.85%   75.68%   -0.18%     
==========================================
  Files          65       64       -1     
  Lines       18523    18249     -274     
==========================================
- Hits        14051    13812     -239     
+ Misses       3466     3453      -13     
+ Partials     1006      984      -22     

see 27 files with indirect coverage changes

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[github-actions]

This PR is stale because it has been open for 90 days with no activity. Update this PR or it will be automatically closed in 30 days.