feat(v11): Drop TypeScript 3.8 support

[logaretm]

Summary

Removes support for generating and publishing TypeScript 3.8 downleveled type definitions across all packages.

The changes simplify the build process by eliminating scripts, dependencies, and configuration related to downleveling types, and update test and project configuration accordingly.

closes #18477

TODO:

• Remove all downlevel scripts
• Remove all related type declarations in package.json
• Update and Removed vendored types specific to 3.8
• Target a new minimum TS version > 4.0
• Update TS.38 tests to use the new minimum version

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⚠️ Will be parked until v11 is ready to go ⚠️

[linear]

JS-1293 Drop TypeScript 3.8 support

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	9,285	-	11,145	-17%
GET With Sentry	1,696	18%	1,889	-10%
GET With Sentry (error only)	5,741	62%	7,659	-25%
POST Baseline	1,194	-	1,171	+2%
POST With Sentry	593	50%	582	+2%
POST With Sentry (error only)	1,009	85%	1,039	-3%
MYSQL Baseline	3,215	-	4,024	-20%
MYSQL With Sentry	494	15%	600	-18%
MYSQL With Sentry (error only)	2,717	85%	3,153	-14%

View base workflow run