fix(migrations): on cockroach db wrap migration execution on the shadow db into a transaction to speed it up

[FGoessler]

This PR attempts to mitigate prisma/prisma#12384 by applying the "run DDL statements in transaction" workaround for our shadow db creation. This should significantly speed up commands like prisma migrate dev for CockroachDB users.

Prisma needs the shadow db to have a reference point to compare the current with the desired state of the database. These shadow databases get created from scratch every time and are usually very fast to setup, but not on CockroachDB.

Note that we do NOT apply this transaction workaround when interfacing with the user's production database when actually applying the migrations.

/integration

[codspeed-hq]

CodSpeed Performance Report

Merging #5138 will not alter performance

_{Comparing fix/cockroachdb-slow-migrations-workaround (7f2ebe4) with main (75c3406)}

Summary

✅ 11 untouched benchmarks

[github-actions]

WASM Query Engine file Size

Engine	This PR	Base branch	Diff
Postgres	2.120MiB	2.120MiB	0.000B
Postgres (gzip)	848.486KiB	848.487KiB	-1.000B
Mysql	2.082MiB	2.082MiB	0.000B
Mysql (gzip)	834.399KiB	834.400KiB	-1.000B
Sqlite	1.990MiB	1.990MiB	0.000B
Sqlite (gzip)	797.975KiB	797.975KiB	0.000B

[jacek-prisma]

Do we have confidence this actually makes a difference? I see it takes about the same amount of time on CI:
https://github.com/prisma/prisma-engines/actions/runs/13018471970/job/36313446720
https://github.com/prisma/prisma-engines/actions/runs/13011750014/job/36290928973

[FGoessler]

Do we have confidence this actually makes a difference? I see it takes about the same amount of time on CI: https://github.com/prisma/prisma-engines/actions/runs/13018471970/job/36313446720 https://github.com/prisma/prisma-engines/actions/runs/13011750014/job/36290928973

On my local example I get from ~2min to ~10sec for a prisma migrate dev. :)