scripts/run-tests-miri: Disable isolation

fake_i2c's test_no_device_response calls std::thread::sleep, which
fails the test if isolation is enabled.

BUG=None
TEST=./scripts/run-tests-miri

Change-Id: I9cda254ecc0c90909e4f856060aae942dcdbcad9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/hps-firmware/+/3686110
Reviewed-by: Dan Callaghan <dcallagh@chromium.org>
Tested-by: David Lattimore <dml@chromium.org>
Commit-Queue: David Lattimore <dml@chromium.org>
Reviewed-by: Jakub Młynarczyk <jakubm@chromium.org>
diff --git a/scripts/run-tests-miri b/scripts/run-tests-miri
index 1895bdf..1d6c2e2 100755
--- a/scripts/run-tests-miri
+++ b/scripts/run-tests-miri
@@ -16,6 +16,10 @@
 
 cd "${PROJECT_ROOT}/rust"
 
+# exclude TERM for a modest speedup, as per:
+# https://github.com/rust-lang/miri/issues/1702
+export MIRIFLAGS="-Zmiri-disable-isolation -Zmiri-env-exclude=TERM"
+
 # We exclude hps-factory from miri tests because its build.rs builds lots of
 # other crates that are time-consuming to build.
 cargo \