Dedup TopoFileLoading

[steiler]

Related to #2225 this dedups the code for loading topologies, where we've had a seperate implementation for the Destroy action.

[hellt]

great catch. ty!

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 51.55%. Comparing base (3dea806) to head (4d3e872).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/destroy.go	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2226      +/-   ##
==========================================
+ Coverage   51.54%   51.55%   +0.01%     
==========================================
  Files         171      171              
  Lines       12625    12617       -8     
==========================================
- Hits         6507     6505       -2     
+ Misses       5211     5208       -3     
+ Partials      907      904       -3     

Files with missing lines	Coverage Δ
cmd/destroy.go	79.46% <66.66%> (+3.63%)	⬆️