test(nextjs): Remove Next 13 and pin Next 14 canary and latest tests

[Lms24]

Looks like we tested canary and latest versions of NextJS 13 and 14 in a way that we'd actually always pull in the latest 15 (canary) versions. This PR fixes this by:

• removing Next 13 canary tests (these haven't been updated in more than 2 years)
• Pinning Next 13 latest to @next-13
• Pining Next 14 canary to ~14.3.0-canary.0
• Pinning Next 14 latest to @next-14

[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	8,619	-	9,109	-5%
GET With Sentry	1,184	14%	1,225	-3%
GET With Sentry (error only)	5,808	67%	5,775	+1%
POST Baseline	1,171	-	1,143	+2%
POST With Sentry	457	39%	451	+1%
POST With Sentry (error only)	1,028	88%	991	+4%
MYSQL Baseline	3,261	-	3,325	-2%
MYSQL With Sentry	390	12%	444	-12%
MYSQL With Sentry (error only)	2,638	81%	2,720	-3%

View base workflow run