test(nextjs): Add next@16 e2e test

[chargome]

• adds a new next 16 test
• removes canary testing for app dir and pages dir tests (this is becoming too cumbersome to maintain across canary/bundler versions etc. – will instead move these tests into next 16 going forward)

Note that next@canary will now always resolve to next@16

[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	8,432	-	8,966	-6%
GET With Sentry	1,364	16%	1,412	-3%
GET With Sentry (error only)	5,966	71%	6,242	-4%
POST Baseline	1,167	-	1,211	-4%
POST With Sentry	496	43%	531	-7%
POST With Sentry (error only)	1,035	89%	1,089	-5%
MYSQL Baseline	3,279	-	3,373	-3%
MYSQL With Sentry	435	13%	484	-10%
MYSQL With Sentry (error only)	2,686	82%	2,768	-3%

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