[Access] Reduce logging for script executions

[peterargue]

This PR reduces logging related to script execution on Access nodes by making the following changes:

• Log script results comparison differences at Debug level
• Use the logging frequency gate for all log messages that contain the script. When the script has been logged recently, just log the hash
• Log script results in base64 instead of hex.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 53.12500% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 55.83%. Comparing base (55fd3bb) to head (087b11e).

Files	Patch %	Lines
engine/access/rpc/backend/backend_scripts.go	31.81%	12 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5959      +/-   ##
==========================================
+ Coverage   55.81%   55.83%   +0.01%     
==========================================
  Files        1129     1129              
  Lines       89205    89210       +5     
==========================================
+ Hits        49794    49808      +14     
+ Misses      34656    34643      -13     
- Partials     4755     4759       +4     

Flag	Coverage Δ
unittests	55.83% <53.12%> (+0.01%)	⬆️

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[jordanschalm]

Not a part of your diff, but we should move this up to immediately after the error is returned, on line 246.

[jordanschalm]

Suggested change

	// shouldLogScript checks if the script hash is unique in the time window
	// shouldLogScript checks whether we should log a script, based on whether we have seen it recently
	// and the current log level.