Use default Xcode for macOS CI

Summary: Update the generated mvfst macOS workflows to point `DEVELOPER_DIR` at `/Applications/Xcode.app/Contents/Developer` instead of the retired Xcode 16.2 path. This matches the current workflow generator and prevents `xcrun` from failing when GitHub rotates runner images.

Reviewed By: jbeshay

Differential Revision: D115296030

fbshipit-source-id: 261ab7581d893747e5da44795407c89de97ece50

Author: sandarsh

.github/workflows/getdeps_mac.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: macOS-latest
     timeout-minutes: 60
     env:
-      DEVELOPER_DIR: /Applications/Xcode_16.2.app/Contents/Developer
+      DEVELOPER_DIR: /Applications/Xcode.app/Contents/Developer
       CC: /opt/homebrew/opt/llvm/bin/clang
       CXX: /opt/homebrew/opt/llvm/bin/clang++
       SCCACHE_GHA_ENABLED: "on"