Remove uses of context.Background()

[fridrik01]

We should only use this in top-level code like in main and tests and such as context.Background is not cancellable

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 27.11%. Comparing base (2afec05) to head (5f57ce8).

Files with missing lines	Patch %	Lines
beacon/blockchain/process_proposal.go	0.00%	2 Missing ⚠️
da/blob/processor.go	0.00%	1 Missing ⚠️
da/blob/verifier.go	0.00%	1 Missing ⚠️
state-transition/core/state_processor_payload.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2376      +/-   ##
==========================================
- Coverage   27.12%   27.11%   -0.01%     
==========================================
  Files         351      351              
  Lines       15523    15524       +1     
  Branches       20       20              
==========================================
  Hits         4210     4210              
- Misses      11110    11111       +1     
  Partials      203      203              

Files with missing lines	Coverage Δ
da/blob/processor.go	0.00% <0.00%> (ø)
da/blob/verifier.go	0.00% <0.00%> (ø)
state-transition/core/state_processor_payload.go	0.00% <0.00%> (ø)
beacon/blockchain/process_proposal.go	0.00% <0.00%> (ø)