chore(examples): drop examples/restify

[trentm]

This example hasn't been meaningfully updated in 4y and hasn't updated it
deps in 3y. instrumentation-restify is unmaintained. Arguably, restify
itself is unmaintained (no release since 2023). Maintaining this
example is not a good use of our time.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.76%. Comparing base (c8d0991) to head (3c48aac).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2910      +/-   ##
==========================================
- Coverage   89.81%   89.76%   -0.05%     
==========================================
  Files         187      187              
  Lines        9149     9149              
  Branches     1885     1885              
==========================================
- Hits         8217     8213       -4     
- Misses        932      936       +4     

see 1 file with indirect coverage changes

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