[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 (8a3055c) to head (b49bb7c).

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   41.26%   41.24%   -0.02%     
==========================================
  Files        2061     2061              
  Lines      182702   182698       -4     
==========================================
- Hits        75384    75351      -33     
- Misses     101010   101040      +30     
+ Partials     6308     6307       -1     

Flag	Coverage Δ
unittests	41.24% <92.85%> (-0.02%)	⬇️

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