Change metalava repo to use DIST_DIR

We were assuming that the DIST_DIR and CHECKOUT_ROOT/out/dist were the same. In CI, DIST_DIR is set separately, so METALAVA_REPO was pointing to the incorrect location.

Bug: 258477743
Test: presubmit
Change-Id: Ia93703741de3dd1c22c12bf70d650cf3dcf5979f
diff --git a/busytown/impl/build-metalava-and-androidx.sh b/busytown/impl/build-metalava-and-androidx.sh
index d24f86c..b609c1a 100755
--- a/busytown/impl/build-metalava-and-androidx.sh
+++ b/busytown/impl/build-metalava-and-androidx.sh
@@ -46,7 +46,7 @@
 
 # Mac grep doesn't support -P, so use perl version of `grep -oP "(?<=metalavaVersion=).*"`
 export METALAVA_VERSION=`perl -nle'print $& while m{(?<=metalavaVersion=).*}g' $METALAVA_DIR/src/main/resources/version.properties`
-export METALAVA_REPO="$CHECKOUT_ROOT/out/dist/repo/m2repository"
+export METALAVA_REPO="$DIST_DIR/repo/m2repository"
 
 function buildAndroidx() {
   ./frameworks/support/busytown/impl/build.sh $androidxArguments \