ci: Try to remove unused Xcode dirs

src/ci/scripts/select-xcode.sh

@@ -1,11 +1,28 @@
 #!/bin/bash
 # This script selects the Xcode instance to use.
+# It also tries to do some cleanup in CI jobs of unused Xcodes.
 
 set -euo pipefail
 IFS=$'\n\t'
 
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 
 if isMacOS; then
+    # This additional step is to try to remove an Xcode we aren't using because each one is HUGE
+    old_xcode="$(xcode-select --print-path)"
+    old_xcode="${old_xcode%/*}" # pop a dir
+    old_xcode="${old_xcode%/*}" # twice
+    if [[ $old_xcode =~ $SELECT_XCODE ]]; then
+        echo "xcode-select.sh's brutal hack may not be necessary?"
+        exit 1
+    elif [[ $SELECT_XCODE =~ "16" ]]; then
+        echo "Using Xcode 16? Please fix xcode-select.sh"
+        exit 1
+    fi
+    if [ $CI ]; then # just in case someone sources this on their real computer
+        sudo rm -rf "${old_xcode}"
+        xcode_16="${old_xcode%/*}/Xcode-16.0.0.app"
+        sudo rm -rf "${xcode_16}"
+    fi
     sudo xcode-select -s "${SELECT_XCODE}"
 fi