nix: remove uneeded slocat

slocat was introduced to test pipeline mode (see https://github.com/PostgREST/postgrest/pull/2682),
but pipeline mode was not merged https://github.com/PostgREST/postgrest/pull/2707.

So it's really not needed on the loadtests.

default.nix

@@ -44,7 +44,6 @@ let
       allOverlays.checked-shell-script
       allOverlays.gitignore
       (allOverlays.haskell-packages { inherit compiler; })
-      allOverlays.slocat
     ];
 
   # Evaluated expression of the Nixpkgs repository.

nix/overlays/default.nix

@@ -3,5 +3,4 @@
   checked-shell-script = import ./checked-shell-script;
   gitignore = import ./gitignore.nix;
   haskell-packages = import ./haskell-packages.nix;
-  slocat = import ./slocat.nix;
 }

nix/overlays/slocat.nix

@@ -1,13 +0,0 @@
-_: prev:
-{
-  slocat = prev.buildGoModule {
-    name = "slocat";
-    src = prev.fetchFromGitHub {
-      owner = "robx";
-      repo = "slocat";
-      rev = "52e7512c6029fd00483e41ccce260a3b4b9b3b64";
-      sha256 = "sha256-qn6luuh5wqREu3s8RfuMCP5PKdS2WdwPrujRYTpfzQ8=";
-    };
-    vendorHash = null;
-  };
-}

nix/tools/loadtest.nix

@@ -140,9 +140,7 @@ let
           mixed)
             # shellcheck disable=SC2145
             ${withTools.withPg} -f "$_arg_testdir"/fixtures.sql \
-            ${withTools.withSlowPg} \
             ${withTools.withPgrst} -m "$_arg_monitor" \
-            ${withTools.withSlowPgrst} \
             sh -c "cd \"$_arg_testdir\" && \
             ${runner} -targets targets.http -output \"$abs_output\" \"''${_arg_leftovers[@]}\""
             ;;

nix/tools/withTools.nix

@@ -6,7 +6,6 @@
 , postgresqlVersions
 , postgrest
 , python3Packages
-, slocat
 , writeText
 , writers
 }:
@@ -185,81 +184,6 @@ let
 
   withPg = withTmpDb (builtins.head postgresqlVersions);
 
-  withSlowPg =
-    checkedShellScript
-      {
-        name = "postgrest-with-slow-pg";
-        docs = "Run the given command with simulated high latency postgresql";
-        args =
-          [
-            "ARG_POSITIONAL_SINGLE([command], [Command to run])"
-            "ARG_LEFTOVERS([command arguments])"
-            "ARG_USE_ENV([PGHOST], [], [PG host (socket name)])"
-            "ARG_USE_ENV([PGDELAY], [0ms], [extra PG latency (duration)])"
-          ];
-        positionalCompletion = "_command";
-        workingDir = "/";
-        redirectTixFiles = false;
-        withTmpDir = true;
-      }
-      ''
-        delay="''${PGDELAY:-0ms}"
-        echo "delaying data to/from postgres by $delay"
-
-        REALPGHOST="$PGHOST"
-        export PGHOST="$tmpdir/socket"
-        mkdir -p "$PGHOST"
-
-        ${slocat}/bin/slocat -delay "$delay" -src "$PGHOST/.s.PGSQL.5432" -dst "$REALPGHOST/.s.PGSQL.5432" &
-        SLOCAT_PID=$!
-        # shellcheck disable=SC2317
-        stop_slocat() {
-          kill "$SLOCAT_PID" || true
-          wait "$SLOCAT_PID" || true
-        }
-        trap stop_slocat EXIT
-        sleep 1 # should wait for socket file to appear instead
-
-        ("$_arg_command" "''${_arg_leftovers[@]}")
-      '';
-
-  withSlowPgrst =
-    checkedShellScript
-      {
-        name = "postgrest-with-slow-postgrest";
-        docs = "Run the given command with simulated high latency postgrest";
-        args =
-          [
-            "ARG_POSITIONAL_SINGLE([command], [Command to run])"
-            "ARG_LEFTOVERS([command arguments])"
-            "ARG_USE_ENV([PGRST_SERVER_UNIX_SOCKET], [], [PostgREST host (socket name)])"
-            "ARG_USE_ENV([PGRST_DELAY], [0ms], [extra PostgREST latency (duration)])"
-          ];
-        positionalCompletion = "_command";
-        workingDir = "/";
-        redirectTixFiles = false;
-        withTmpDir = true;
-      }
-      ''
-        delay="''${PGRST_DELAY:-0ms}"
-        echo "delaying data to/from PostgREST by $delay"
-
-        REAL_PGRST_SERVER_UNIX_SOCKET="$PGRST_SERVER_UNIX_SOCKET"
-        export PGRST_SERVER_UNIX_SOCKET="$tmpdir/postgrest.socket"
-
-        ${slocat}/bin/slocat -delay "$delay" -src "$PGRST_SERVER_UNIX_SOCKET" -dst "$REAL_PGRST_SERVER_UNIX_SOCKET" &
-        SLOCAT_PID=$!
-        # shellcheck disable=SC2317
-        stop_slocat() {
-          kill "$SLOCAT_PID" || true
-          wait "$SLOCAT_PID" || true
-        }
-        trap stop_slocat EXIT
-        sleep 1 # should wait for socket file to appear instead
-
-        ("$_arg_command" "''${_arg_leftovers[@]}")
-      '';
-
   withGit =
     let
       name = "postgrest-with-git";
@@ -455,9 +379,7 @@ buildToolbox
     inherit
       withGit
       withPgAll
-      withPgrst
-      withSlowPg
-      withSlowPgrst;
+      withPgrst;
   } // builtins.listToAttrs (
     # Create a `postgrest-with-pg-` for each PostgreSQL version
     builtins.map (pg: { inherit (pg) name; value = withTmpDb pg; }) postgresqlVersions