test(download): use CURRENT_ENGINES_HASH and debug urlExists()

[Jolg42]

example output from CI (before)
https://github.com/prisma/prisma/actions/runs/4068739470/jobs/7007659364#step:25:741

> @prisma/fetch-engine@0.0.0 test /Users/runner/work/prisma/prisma/packages/fetch-engine
> jest
[...]
  console.log
    info The engine commit 323c8a1169351067817dd9f83076b2f8afad856c is not yet done. We're skipping it as we're in dev. Missing urls: 1

      at log (src/getLatestTag.ts:85:17)

  console.log
    info The engine commit 5cb8c36d6b81f775275971664983f06409ed8c6d is not yet done. We're skipping it as we're in dev. Missing urls: 3

      at log (src/getLatestTag.ts:85:17)

  console.log
    info The engine commit 1c3c1107e1e7d1d0ac19e76076bbaff83fc8cb87 is not yet done. We're skipping it as we're in dev. Missing urls: 1

      at log (src/getLatestTag.ts:85:17)
          at runMicrotasks (<anonymous>)

  console.log
    info The engine commit f2fdde4b88a31caca7d51e6b6e0c21cc54869522 is not yet done. We're skipping it as we're in dev. Missing urls: 2

      at log (src/getLatestTag.ts:85:17)
          at runMicrotasks (<anonymous>)

[Jolg42]

Note: I think we actually wanted to remove "latest" completely
Related: #16685

[Jolg42]

Already done