Use reflect to construct a Record in logtest

[MrAlias]

The testing functionality of the logtest package is limited currently by the default behavior of the SDK.

• There is no way to not set an instrumentation scope
• The attribute limits cannot be set, nor could they be set independent of the attribute add operation
• The zero value of the produced Record by RecordFactory{}.NewRecord() is not a zero value Record

This PR applies the following changes to address these short comings.

• Change NewRecord to construct the Record exactly instead of using the default SDK.
• Update InstrumentationScope to be a *instrumentation.Scope so the zero value can correctly not set the instrumentation scope of the produced record.

Addresses #5264 (comment)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.5%. Comparing base (e0ed6a3) to head (d669489).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5275   +/-   ##
=====================================
  Coverage   84.4%   84.5%           
=====================================
  Files        265     265           
  Lines      17523   17505   -18     
=====================================
- Hits       14806   14795   -11     
+ Misses      2408    2401    -7     
  Partials     309     309           

Files	Coverage Δ
sdk/log/logtest/factory.go	100.0% <100.0%> (+14.2%)	⬆️

... and 1 file with indirect coverage changes