fix: only add log middleware to not found handler when enabled

[AlexLast]

The notFoundHandler() function builds its own chain, that will always contain the log middleware, even when Middlewares.Log = false.

This change ensures the log handler is only added to this chain conditionally.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.21%. Comparing base (2629636) to head (0b363f5).
Report is 8 commits behind head on master.

Additional details and impacted files

Files	Coverage Δ
rest/engine.go	100.00% <100.00%> (ø)

... and 252 files with indirect coverage changes