refactor: only have a single digest version variable (#14131) #39240

Job	Run time
Bootstrap (ubuntu-latest)	4m 8s
Ensure no files with CRLF line endings are committed to the repo	4s
Nix Tests (ubuntu-latest)	7m 24s
Nix Build 4.14 (ubuntu-latest)	1m 53s
Format	1m 33s
Cygwin Build	4m 15s
Documentation	1m 0s
Test that the utop dev tool can be built and run	9m 7s
Nix Build (macos-latest)	3m 4s
Build with OxCaml (ubuntu-latest)	17m 36s
Nix Build (ubuntu-latest)	1m 16s
Rocq 9.2 (native)	9m 52s
Wasm_of_ocaml	7m 39s
Building Dune with OxCaml	32m 13s
Create local opam switch (ubuntu-latest, 5)	5m 36s
Build microbenchmarks	2m 1s
Create local opam switch (macos-latest, 5)	7m 49s
Rocq 9.2	2m 35s
Build (4.14.x, 4.14.x, macos-latest)	2m 57s
Build (ocaml-variants.5.6.0+trunk, ocaml-variants.5.6.0+trunk, ubuntu-latest)	1m 25s
Build (ocaml-base-compiler.5.4.0,system-mingw, windows-latest, ocaml-compiler.5.4.0-system-mingw,...	11m 37s
Build (5.4.x, 5.4.x, ubuntu-latest, true)	6m 16s
Build (ocaml-compiler.5.4.0,system-msvc, windows-latest, ocaml-compiler.5.4.0-system-msvc, true)	9m 30s
Build (4.14.x, 4.14.x, ubuntu-latest)	1m 15s
Build (5.4.x, 5.4.x, macos-latest, true)	11m 25s
Build (5.4.x, 5.4.x, macos-15-intel)	4m 25s
Build (ocaml-variants.4.14.2+options,ocaml-option-32bit, ocaml-variants.4.14.2-ocaml-option-32bit...	4m 1s
	2h 51m 56s

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