Switch compute-related locales to C.UTF-8 by default (#6746)

Right now, our environments create databases with the C locale, which is
really unfortunate for users who have data stored in other languages
that they want to analyze. For instance, show_trgm on Hebrew text
currently doesn't work in staging or production.

I don't envision this being the final solution. I think this is just a
way to set a known value so the pageserver doesn't use its parent
environment. The final solution to me is exposing initdb parameters to
users in the console. Then they could use a different locale or encoding
if they so chose.

Signed-off-by: Tristan Partin <tristan@neon.tech>

libs/utils/scripts/restore_from_wal.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -euxo pipefail
 
@@ -6,9 +6,44 @@ PG_BIN=$1
 WAL_PATH=$2
 DATA_DIR=$3
 PORT=$4
+PG_VERSION=$5
 SYSID=$(od -A n -j 24 -N 8 -t d8 "$WAL_PATH"/000000010000000000000002* | cut -c 3-)
+
+# The way that initdb is invoked must match how the pageserver runs initdb.
+function initdb_with_args {
+    local cmd=(
+        "$PG_BIN"/initdb
+        -E utf8
+        -U cloud_admin
+        -D "$DATA_DIR"
+        --locale 'C.UTF-8'
+        --lc-collate 'C.UTF-8'
+        --lc-ctype 'C.UTF-8'
+        --lc-messages 'C.UTF-8'
+        --lc-monetary 'C.UTF-8'
+        --lc-numeric 'C.UTF-8'
+        --lc-time 'C.UTF-8'
+        --sysid="$SYSID"
+    )
+
+    case "$PG_VERSION" in
+        14)
+            # Postgres 14 and below didn't support --locale-provider
+            ;;
+        15 | 16)
+            cmd+=(--locale-provider 'libc')
+            ;;
+        *)
+            # Postgres 17 added the builtin provider
+            cmd+=(--locale-provider 'builtin')
+            ;;
+    esac
+
+    eval env -i LD_LIBRARY_PATH="$PG_BIN"/../lib "${cmd[*]}"
+}
+
 rm -fr "$DATA_DIR"
-env -i LD_LIBRARY_PATH="$PG_BIN"/../lib "$PG_BIN"/initdb -E utf8 -U cloud_admin -D "$DATA_DIR" --sysid="$SYSID"
+initdb_with_args
 echo "port=$PORT" >> "$DATA_DIR"/postgresql.conf
 echo "shared_preload_libraries='\$libdir/neon_rmgr.so'" >> "$DATA_DIR"/postgresql.conf
 REDO_POS=0x$("$PG_BIN"/pg_controldata -D "$DATA_DIR" | grep -F "REDO location"| cut -c 42-)