PRESUBMIT.cfg: don't run Rust builds and tests

Don't run scripts/run-tests on every commit before upload.

The important stuff in that script is now covered by CQ (namely:
compiling HPS MCU firmware, FPGA firmware, host tools, and running Rust
unit tests and gateware unit tests) which is the best place for it.
Developers can continue to invoke scripts/run-tests or some more
specific test commands locally to validate their changes. But we don't
need to force everyone to do it on every commit.

BUG=b:215275939
TEST=repo upload

Change-Id: I16b33aacac559d2b2052ef984ed3d6548b3e3667
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/hps-firmware/+/3617828
Tested-by: Dan Callaghan <dcallagh@chromium.org>
Commit-Queue: Dan Callaghan <dcallagh@chromium.org>
Reviewed-by: David Lattimore <dml@chromium.org>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index a3ef025..72c976f 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -6,4 +6,3 @@
 
 [Hook Scripts]
 cros lint = scripts/lint-files ${PRESUBMIT_FILES}
-run-rustc-tests = scripts/run-tests