install ocaml in dockerfile instead of postCreate.sh #9463

Job	Run time
test-devcontainer	4m 3s
build-compiler (ubuntu-24.04, ocaml-variants.5.3.0+options,ocaml-option-static, true, true, linux...	5m 21s
build-compiler (macos-15, 5.3.0, true, darwin-arm64, aarch64-apple-darwin)	7m 44s
build-compiler (ubuntu-24.04, ocaml-variants.5.0.0+options,ocaml-option-static, linux-x64, x86_64...	4m 50s
build-compiler (macos-15-intel, 5.3.0, true, darwin-x64, x86_64-apple-darwin)	10m 37s
build-compiler (windows-2025, 5.3.0, true, win32-x64, x86_64-pc-windows-gnu, .exe)	10m 9s
build-compiler (ubuntu-24.04-arm, ocaml-variants.5.3.0+options,ocaml-option-static, true, true, t...	5m 59s
api-docs	12s
pkg-pr-new	51s
test-integration-rewatch (windows-2025)	4m 59s
test-installation-pnpm (macos-15)	20s
test-integration-rewatch (ubuntu-24.04)	3m 33s
test-installation-npm (macos-15-intel)	31s
test-installation-npm (macos-15)	14s
test-installation-npm (ubuntu-24.04-arm)	18s
test-integration-rewatch (macos-15-intel)	5m 5s
test-installation-npm (ubuntu-24.04)	13s
test-installation-npm (windows-2025)	54s
test-installation-pnpm (ubuntu-24.04-arm)	19s
test-installation-pnpm (macos-15-intel)	32s
test-integration-rewatch (macos-15)	4m 48s
test-installation-pnpm (windows-2025)	36s
test-integration-rewatch (ubuntu-24.04-arm)	2m 53s
test-installation-pnpm (ubuntu-24.04)	16s
publish	1s
	1h 15m 18s

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