fix(setup-postgres.yml): fix missing initdb calls #5019

Job	Run time
nix-eval / eval	1m 21s
no packages to build (aarch64-darwin)	2s
no packages to build (aarch64-linux)	3s
no packages to build (x86_64-linux)	3s
pre-commit-run (aarch64-darwin)	17s
treefmt-check (aarch64-darwin)	16s
treefmt-check (aarch64-linux)	50s
pre-commit-run (aarch64-linux)	1m 0s
pre-commit-run (x86_64-linux)	40s
treefmt-check (x86_64-linux)	41s
run-testinfra / prepare	45s
run-tests / prepare	38s
run-tests / build (orioledb-17)	2m 0s
run-tests / build (15)	2m 27s
run-tests / build (17)	1m 59s
run-testinfra / test-ami-nix (17)	52m 17s
run-testinfra / test-ami-nix (orioledb-17)	52m 32s
run-testinfra / test-ami-nix (15)	57m 26s
	2h 55m 17s

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