Fix tests/runtests.sh

The location of FrameworksWifiTests.apk installed by the script
with adb seems to have changed. The path of the APK contains the
TARGET_ARCH environment variable, which is now fetched
with a similar method as in system/netd/tests/runtests.sh.

Noticed the issue with "lunch aosp_x86_64-eng". Before this fix,
the test script produced an error:

    adb: failed to stat [...]/FrameworksWifiApiTests.apk:
    No such file or directory

Bug: 128603658
Test: ./frameworks/base/wifi/tests/runtests.sh

Change-Id: Id4a33ca89fa21a9a4ef791c5c1c5760e0e2badaf
Signed-off-by: Otto Seiskari <otto.seiskari@indooratlas.com>
diff --git a/wifi/tests/runtests.sh b/wifi/tests/runtests.sh
index 1e0ec37..219a45e 100755
--- a/wifi/tests/runtests.sh
+++ b/wifi/tests/runtests.sh
@@ -19,7 +19,8 @@
 adb root
 adb wait-for-device
 
-adb install -r -g "$OUT/testcases/FrameworksWifiApiTests/arm64/FrameworksWifiApiTests.apk"
+TARGET_ARCH=$($ANDROID_BUILD_TOP/build/soong/soong_ui.bash --dumpvar-mode TARGET_ARCH)
+adb install -r -g "$OUT/testcases/FrameworksWifiApiTests/$TARGET_ARCH/FrameworksWifiApiTests.apk"
 
 adb shell am instrument --no-hidden-api-checks -w "$@" \
   'android.net.wifi.test/androidx.test.runner.AndroidJUnitRunner'