Remove `ANDROID_TZDATA_ROOT` overriding logic on device in `art` script.

Test: Run Libcore tests on device
Bug: 124425036
Bug: 121117762
Change-Id: I17173f1b672e197564e79b3f96b4a27c5543179b
diff --git a/tools/art b/tools/art
index 94ce572..4898781 100644
--- a/tools/art
+++ b/tools/art
@@ -432,31 +432,13 @@
   # - on host, `ANDROID_TZDATA_ROOT` is expected to be
   #   "$ANDROID_ROOT/com.android.tzdata";
   # - on target, `ANDROID_TZDATA_ROOT` is expected to be
-  #   "$ANDROID_ROOT/../apex/com.android.tzdata".
+  #   "/apex/com.android.tzdata".
   #
   # We use the presence/absence of the `$ANDROID_ROOT/../apex` directory to
   # determine whether we are on target or host (this is brittle, but simple).
   if [ -d "$ANDROID_ROOT/../apex" ]; then
     # Target case.
-    #
-    # We should be setting `ANDROID_TZDATA_ROOT` to
-    # "$ANDROID_ROOT/../apex/com.android.tzdata" here. However, the Time Zone
-    # Data APEX is not (yet) supported by the ART Buildbot setup (see
-    # b/121117762); and yet libcore / ICU code depends on `ANDROID_TZDATA_ROOT`
-    # to find data files.
-    #
-    # As a temporary workaround, we:
-    # - make the ART Buildbot build script (art/tools/buildbot-build.sh) also
-    #   generate the data files in `/system/etc/tzdata_module` on
-    #   device (these files are normally only put in the Time Zone Data APEX
-    #   on device);
-    # - set `ANDROID_TZDATA_ROOT` to `$ANDROID_ROOT/etc/tzdata_module` (i.e.
-    #   "/system/etc/tzdata_module") here.
-    #
-    # TODO(b/121117762): Set `ANDROID_TZDATA_ROOT` to
-    # "$ANDROID_ROOT/../apex/com.android.tzdata" when the Time Zone Data APEX
-    # is fully supported on the ART Buildbot and Golem.
-    ANDROID_TZDATA_ROOT=$ANDROID_ROOT/etc/tzdata_module
+    ANDROID_TZDATA_ROOT="/apex/com.android.tzdata"
   else
     # Host case.
     ANDROID_TZDATA_ROOT="$ANDROID_ROOT/com.android.tzdata"