Cardano Updates

The test runs `runghc conduit-test.hs` against `env.ghc` /
`envDefault.ghc`.  With v2's default
`exposePackagesVia = "cabal-store"` only `~/.cabal/store` is
seeded; plain `runghc` doesn't read the cabal store, so it failed
with "Could not find module 'Conduit'".  Switch the three shells
to `"ghc-pkg"` so `env.ghc` is wrapped to stack the composed
package.db via `GHC_ENVIRONMENT`.  Mirrors the earlier fix in
`tests.shell-for-setup-deps`.

- MempoolCapacityBytesOverride (See https://github.com/input-output-hk/ouroboros-leios/blob/ebc1f7c76b34e3d4f1b28485b720ed324633a6b3/demo/proto-devnet/config/config.yaml#L9)
- MempoolTimeoutCapacity

`packages.HsOpenSSL.ghcOptions` previously held a
`-optc=-Wno-incompatible-pointer-types` workaround.  v2's slices
read configure-args from plan.json; module-level `ghcOptions`
never reach plan-nix's plan.json, so under v2 the slice picked up
the flag (via comp-v2-builder's per-package ghcOptions block) but
plan-nix did not — and the resulting UnitIds diverged
(`HsOpnSSL-0.11.7.10-9ebdbccd` expected vs `-ecc34d19` produced).

Move the workaround into `test/cabal.project.local` under
`package HsOpenSSL ghc-options:` so plan-nix and the slice agree.
Drop the now-unneeded `HsOpenSSL` entry from `package-keys` in
`test/modules.nix`.

Verified against `tests.exe-dlls.build`.

Signed-off-by: Chris Gianelloni <[email protected]>

Re-enables the `broken = isGhcjs && ghc >= 9.6.1` guard that
commit 19b9a5110 commented out while bringing up v2.  The
underlying failure is in ghcjs/emscripten wasm-ld ("section too
large" linking the `-O`-optimized C-backend objects), which
predates v2 and isn't a slicer issue.  Skip the test on ghcjs
again so CI doesn't fail on a pre-existing upstream limitation.

* Avoid attempted rebuilding by `cabal`
* Eliminate the need for restoring cache
* Reduce the size of artifacts passed between `build` and `test`
* Reduce the fragile duplication of logic between `build` and `test`

doctesting has been removed but will be reinstated in a subsequent PR