Fix formatting for TSan CI scaffolding

dune @fmt / ocaml-ci's lint-fmt rejected two short match/if
bindings that fit on a single line. No semantic change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: cuihtlauac

test/irmin-pack/test_multicore.ml

@@ -23,9 +23,7 @@ let src = Logs.Src.create "tests.multicore" ~doc:"Tests"
 module Log = (val Logs.src_log src : Logs.LOG)
 
 let int_env name default =
-  match Sys.getenv_opt name with
-  | Some s -> int_of_string s
-  | None -> default
+  match Sys.getenv_opt name with Some s -> int_of_string s | None -> default
 
 let default_domains = int_env "IRMIN_MULTICORE_DOMAINS" 2
 let test_iter = int_env "IRMIN_MULTICORE_ITER" 1

test/irmin-pack/test_tsan_stress/main.ml

@@ -21,9 +21,7 @@ let run_all () =
     scenarios
 
 let () =
-  let which =
-    if Array.length Sys.argv >= 2 then Sys.argv.(1) else "all"
-  in
+  let which = if Array.length Sys.argv >= 2 then Sys.argv.(1) else "all" in
   match which with
   | "all" -> run_all ()
   | name -> (