tests(swamp): befp testing

[vgonkivs]

Overview

Reworked swamp test for the BEFP

Checklist

• New and updated code has appropriate documentation
• New and updated code has new and/or updated testing
• Required CI checks are passing
• Visual proof for any user facing features like CLI or documentation updates
• Linked issues closed with keywords

[codecov-commenter]

Codecov Report

Merging #2584 (a2111d5) into main (80d6dba) will decrease coverage by 0.10%.
The diff coverage is 23.07%.

@@            Coverage Diff             @@
##             main    #2584      +/-   ##
==========================================
- Coverage   51.13%   51.04%   -0.10%     
==========================================
  Files         158      158              
  Lines       10576    10558      -18     
==========================================
- Hits         5408     5389      -19     
+ Misses       4696     4690       -6     
- Partials      472      479       +7     

Files Changed	Coverage Δ
header/headertest/testing.go	81.30% <ø> (+9.38%)	⬆️
nodebuilder/p2p/opts.go	0.00% <0.00%> (ø)
share/getters/ipld.go	62.22% <25.00%> (-1.74%)	⬇️
share/getters/cascade.go	69.13% <28.57%> (-4.20%)	⬇️

... and 8 files with indirect coverage changes

[distractedm1nd]

Really clean and straightforward