chore: remove old migrations

[Roznovjak]

No description provided.

[github-actions]

Crate versions that have not been updated:

• hydradx-runtime: v173.0.0

Runtime version has not been increased.

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.32% 🎉

Comparison is base (aa6edc9) 68.24% compared to head (e65a3f5) 68.56%.
Report is 2 commits behind head on master.

❗ Current head e65a3f5 differs from pull request most recent head a71c527. Consider uploading reports for the commit a71c527 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #653      +/-   ##
==========================================
+ Coverage   68.24%   68.56%   +0.32%     
==========================================
  Files         156      156              
  Lines       11796    11730      -66     
==========================================
- Hits         8050     8043       -7     
+ Misses       3746     3687      -59     

Files Changed	Coverage Δ
runtime/hydradx/src/lib.rs	3.24% <ø> (ø)
runtime/hydradx/src/migrations.rs	0.00% <0.00%> (ø)

... and 3 files with indirect coverage changes

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