Merge pull request swiftlang#21430 from apple/shahmishal/update-toolchain-plist

Update the toolchain plist by moving SWIFT_USE_DEVELOPMENT_TOOLCHAIN_…

Author: shahmishal

utils/build-script-impl

@@ -3774,8 +3774,7 @@ function build_and_test_installable_package() {
           call ${PLISTBUDDY_BIN} -c "Add OverrideBuildSettings:SWIFT_DISABLE_REQUIRED_ARCLITE string 'YES'" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
           call ${PLISTBUDDY_BIN} -c "Add OverrideBuildSettings:SWIFT_LINK_OBJC_RUNTIME string 'YES'" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
           call ${PLISTBUDDY_BIN} -c "Add OverrideBuildSettings:SWIFT_DEVELOPMENT_TOOLCHAIN string 'YES'" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
-          call ${PLISTBUDDY_BIN} -c "Add DefaultBuildSettings dict" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
-          call ${PLISTBUDDY_BIN} -c "Add DefaultBuildSettings:SWIFT_USE_DEVELOPMENT_TOOLCHAIN_RUNTIME string 'YES'" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
+          call ${PLISTBUDDY_BIN} -c "Add OverrideBuildSettings:SWIFT_USE_DEVELOPMENT_TOOLCHAIN_RUNTIME string 'YES'" "${DARWIN_TOOLCHAIN_INFO_PLIST}"
 
           call chmod a+r "${DARWIN_TOOLCHAIN_INFO_PLIST}"