[infra] adjust-pages.pl: drop spec-patching code

[chalin]

• Followup to Update opentelemetry-specification version to v1.30.0 #4009
• Contributes to Docsy breaking change: adjust for new path_base_for_github_subdir  #3922

There are no changes to the generated site files (other than the site timestamp):

$ npm run build
...
$ (cd public && git diff -bw --ignore-blank-lines) | grep ^diff
diff --git a/site/index.html b/site/index.html