fix: missing telemetry in mysql2 when importing only promise API

[macno]

Which problem is this PR solving?

See #2590

Short description of the changes

Patch lib/connection.js that is always imported

[codecov]

Codecov Report

Attention: Patch coverage is 90.32258% with 3 lines in your changes missing coverage. Please review.

Project coverage is 90.96%. Comparing base (5f214eb) to head (7182d08).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...etry-instrumentation-mysql2/src/instrumentation.ts	93.10%	2 Missing ⚠️
.../opentelemetry-instrumentation-mysql2/src/utils.ts	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2662   +/-   ##
=======================================
  Coverage   90.95%   90.96%           
=======================================
  Files         172      172           
  Lines        8119     8137   +18     
  Branches     1646     1649    +3     
=======================================
+ Hits         7385     7402   +17     
- Misses        734      735    +1     

Files with missing lines	Coverage Δ
.../opentelemetry-instrumentation-mysql2/src/utils.ts	91.30% <50.00%> (-1.88%)	⬇️
...etry-instrumentation-mysql2/src/instrumentation.ts	95.60% <93.10%> (+0.93%)	⬆️

[pichlermarc]

Overall looks good, thanks for chasing this down. 🙌
Just one comment nit and one blocker around addSpanProcessor.

Due to the re-format and change in nesting, the diff here initially looked more daunting than it actually was 🙂

[macno]

Overall looks good, thanks for chasing this down. 🙌 Just one comment nit and one blocker around addSpanProcessor.

Due to the re-format and change in nesting, the diff here initially looked more daunting than it actually was 🙂

yeah, sorry about that, but I had to find a way to use different before/after blocks.

I'll take care of the suggestions, thank you!

[david-luna]

nit: by importing the types at the top of the file you can avoid loading twice the module which may improve perf (although not noticeable) and avoid any possible odd scenario. Actually I found quite misfortunate to name mysqlTypes and mysqlTypesProm the imported modules. The types in the names is quite misleading since it's the actual module object