refactor(engine): remove [Dune_sexp] from the engine #27931

Job	Run time
Coverage (4.14.x)	9m 47s
Build microbenchmarks	5m 9s
Coq 8.16.1	8m 44s
Build (macos-latest, 4.14.x)	16m 16s
Build (ubuntu-latest, 4.14.x)	8m 36s
Create local opam switch (macos-latest, 5)	10m 17s
Build (ocaml-variants.5.3.0+trunk, ubuntu-latest, true)	1m 42s
Documentation	1m 17s
Format	2m 29s
Create local opam switch (macos-latest, 4.14)	10m 29s
Build (5.1.x, ubuntu-latest, true)	2m 48s
Create local opam switch (ubuntu-latest, 5)	5m 30s
Build (5.1.x, macos-latest, true)	2m 59s
Build (4.14.x, macos-13, true)	4m 54s
Create local opam switch (ubuntu-latest, 4.14)	5m 53s
Build monorepo benchmark docker image	4m 9s
Nix (macos-latest)	1m 55s
Build (ocaml-base-compiler.4.14.2,system-msvc, windows-latest)	10m 25s
Nix (ubuntu-latest)	59s
Build (ocaml-base-compiler.4.14.2,system-mingw, windows-latest)	9m 51s
Build (4.13.x, ubuntu-latest, true)	1m 36s
Build (4.08.x, ubuntu-latest, true)	1m 46s
Build (4.04.x, ubuntu-latest, true, true)	7m 37s
Build (4.02.x, ubuntu-latest, true)	4m 2s
	2h 19m 10s

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