Use a runtime Docker image that has libffi and gmp

Context

Depends on opam-repository!379 (merged)

This is an excerpt of !6962 (merged) in which I try to clean the set of executables that are put in Docker images. In particular, for master, I add experimental executables, including octez-sc-rollup-node-alpha. But this executable does not actually run because of the following error (see https://gitlab.com/tezos/tezos/-/jobs/3387190127):

Checking version of octez-sc-rollup-node-alpha: Error loading shared library libffi.so.8: No such file or directory (needed by /usr/local/bin/octez-sc-rollup-node-alpha)
Error loading shared library libgmpxx.so.4: No such file or directory (needed by /usr/local/bin/octez-sc-rollup-node-alpha)
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_closure_alloc: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_prep_closure_loc: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_call: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_prep_cif: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_closure_free: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_pointer: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_double: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_sint32: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_float: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_void: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_uint16: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_sint16: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_sint64: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_uint8: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_uint64: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_uint32: symbol not found
Error relocating /usr/local/bin/octez-sc-rollup-node-alpha: ffi_type_sint8: symbol not found

With the Docker images built by opam-repository!379 (merged) the error is gone (see https://gitlab.com/tezos/tezos/-/jobs/3388398252 — which failed but for an unrelated reason):

Checking version of octez-sc-rollup-node-alpha: '1bb86b67 (2022-11-28 14:43:23 +0100) (0.0+dev)', OK!

Manually testing the MR

Check the CI.

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