chore(instrumentation-express, instrumentation-fastify): drop unused devDep @types/express

[trentm]

For some background, in #1804 the @types/express dep was removed from instr-express's dependencies after some long discussion. At the time it was moved to a devDep.

However, @types/express isn't used at all in these packages. Can we drop them?
Or is there some slight downside for possible IDE completion when developing express examples or similar in this repo by removing these?

Note that I only bothered looking at these because of this bot PR to update these deps: #2925 (comment)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.79%. Comparing base (9d90781) to head (a28636c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

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##             main    #2962   +/-   ##
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  Coverage   89.79%   89.79%           
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  Files         188      188           
  Lines        9222     9222           
  Branches     1900     1900           
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  Hits         8281     8281           
  Misses        941      941           

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[david-luna]

In @opentelemetry/instrumentation-express the types are used internally

So the compilation step should fail if the types are not present. But if we list where the dependency is

npm ls @types/express
[email protected] /Users/david/Documents/repos/otel/opentelemetry-js-contrib
├─┬ @opentelemetry/[email protected] -> ./packages/instrumentation-express
│ └── @types/[email protected]
├─┬ @opentelemetry/[email protected] -> ./packages/instrumentation-fastify
│ └── @types/[email protected] deduped
└─┬ @opentelemetry/[email protected] -> ./packages/instrumentation-koa
  └─┬ @types/[email protected]
    └─┬ @types/[email protected]
      └── @types/[email protected] deduped

We can see that we get the express types as a dependency from @types/koa so the editor and the compiler can see them because they are installed at the root level. That would explain why compilation succeeds.

IMHO removing @types/express from @opentelemetry/instrumentation-fastify is okay but we should keep them for @opentelemetry/instrumentation-express. @opentelemetry/instrumentation-koa is unlikely to change but there is the possibility @types/koa gets an update that removes the dependency.