Temporarily use JAVA8 for running robolectric 3.5.1.

Robolectric 3.5.1 *should* support running under OpenJDK 9's java
but it turns out that several tests that were recently migrated
from robolectric 3.4.* to 3.5.1 do not. The exact reasons have not
yet been investigated (it looks like there are different reasons
for different tests).

Since the default toolchain switched to OpenJDK 9 today, this
broke the run_host_tests target on internal master. To give us
more time to investigate the breakages, and to avoid the disruption
from changing the default toolchain back and forth, this CL changes
robolectric 3.5.1 tests to run under OpenJDK 8's bin/java, like
robolectric 3.4.* tests already do. Once the causes of the test
breakages are fixed, this CL should be reverted.

Bug: 70286093
Test: make -j40 showcommands dist \
  RunSettingsRoboTests RunSettingsRoboTests-jacoco \
  RunSettingsLibRoboTests RunSettingsLibRoboTests-jacoco \
  RunSettingsGoogleRoboTests RunSettingsGoogleRoboTests-jacoco \
  RunSuwRoboTests RunSuwRoboTests-jacoco \
  RunTurboRoboTests RunStorageManagerRoboTests \
  RunTvSettingsRoboTests RunTvSettingsRoboTests-jacoco
Change-Id: Id5e8b73f4dec804bf11385338ce3a60f908f04ef