ci: Restore packaging with macOS SDK from Xcode

We now build with Qt 6.9.3, which supports the macOS 26 SDK.
Revert commit baa8cab401 (ci: Revert packaging to macOS 15.5 SDK to
restore cmake-gui rendering, 2025-10-25, v4.2.0-rc2~19^2) and drop
supporting scripts.

Issue: #27325

.gitlab/.gitignore

@@ -12,7 +12,6 @@
 /innosetup
 /jom
 /llvm*
-/MacOS*
 /mingw
 /msvc*
 /ninja*

.gitlab/ci/env_macos_package.sh

@@ -1 +0,0 @@
-. .gitlab/ci/macos-env.sh

.gitlab/ci/macos-env.sh

@@ -1,2 +0,0 @@
-.gitlab/ci/macos.sh
-export SDKROOT="$PWD/.gitlab/MacOSX.sdk"

.gitlab/ci/macos.sh

@@ -1,28 +0,0 @@
-#!/bin/sh
-
-set -e
-
-# This URL is only visible inside of Kitware's network.
-baseurl="https://cmake.org/files/dependencies/internal/macos"
-
-case "$(uname -s)-$(uname -m)" in
-    Darwin-*)
-        shatool="shasum -a 256"
-        sha256sum="427612880d6c40bcef2b0ecb39d92b057ee7a43ec3552fbd4449859991eb1cc6"
-        tarball="MacOSX15.5.sdk.tar.bz2"
-        ;;
-    *)
-        echo "Unrecognized platform $(uname -s)-$(uname -m)"
-        exit 1
-        ;;
-esac
-readonly shatool
-readonly sha256sum
-
-cd .gitlab
-
-echo "$sha256sum  $tarball" > macos.sha256sum
-curl -OL "$baseurl/$tarball"
-$shatool --check macos.sha256sum
-tar xjf "$tarball"
-rm "$tarball" macos.sha256sum

.gitlab/ci/repackage/macos.sh

@@ -1,8 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-
-sdkPath="$(xcrun --show-sdk-path)"
-sdkVers="$(xcrun --show-sdk-version)"
-
-tar cjf "MacOSX${sdkVers}.sdk.tar.bz2" -C "${sdkPath%/*}" --no-fflags "MacOSX.sdk"