ledger: remove wasm downloader

[Fraccaman]

Describe your changes

We are now shipping wasm artifacts together with the chain setup, no need to let the node download artifacts from an untrusted source.

Indicate on which release or other PRs this topic is based on

Checklist before merging to draft

• I have added a changelog
• Git history is in acceptable state

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 15 lines in your changes missing coverage. Please review.

Project coverage is 54.56%. Comparing base (682d7ff) to head (793f4a4).
Report is 17 commits behind head on main.

Files	Patch %	Lines
crates/apps_lib/src/wasm_loader/mod.rs	0.00%	10 Missing ⚠️
crates/apps_lib/src/client/utils.rs	0.00%	4 Missing ⚠️
crates/node/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3598      +/-   ##
==========================================
+ Coverage   54.53%   54.56%   +0.03%     
==========================================
  Files         323      323              
  Lines      113879   113819      -60     
==========================================
+ Hits        62108    62111       +3     
+ Misses      51771    51708      -63     

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