[Access] Improvements for SubscribeTransactionStatuses statuses handling

[Guitarheroua]

Closes #6574

Updated the logic for checking transaction results. The system now always checks local storage first, and if no transaction result is found, it attempts to retrieve it from the execution node.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 41.24%. Comparing base (ed149a7) to head (9ee3d6a).
Report is 82 commits behind head on master.

Files with missing lines	Patch %	Lines
engine/access/rpc/backend/backend_transactions.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6736      +/-   ##
==========================================
+ Coverage   41.19%   41.24%   +0.04%     
==========================================
  Files        2052     2054       +2     
  Lines      182215   182364     +149     
==========================================
+ Hits        75069    75211     +142     
- Misses     100852   100857       +5     
- Partials     6294     6296       +2     

Flag	Coverage Δ
unittests	41.24% <92.85%> (+0.04%)	⬆️

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