OHOS: Run speedometer in CI (#37666)

OHOS: Run speedometer in CI for OHOS.
This also adds the forgotten flag to disable jit for HarmonyOs devices.

Need https://github.com/servo/servo/pull/37636 to be merged first and CI
updated which will be done when this PR is marked ready.

Testing: Custom run:
https://github.com/Narfinger/servo/actions/runs/15927927047/job/44929872906
Bencher output:
https://bencher.dev/perf/servo-ci/reports/4f778f61-699e-4e70-8994-bd526733eab1?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr%2Bcomments&utm_term=servo-ci
No other tests available because CI.

---------

Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>
Signed-off-by: Jonathan Schwender <55576758+jschwe@users.noreply.github.com>
Co-authored-by: Jonathan Schwender <55576758+jschwe@users.noreply.github.com>

python/servo/testing_commands.py

@@ -703,6 +703,8 @@ class MachCommands(CommandBase):
                 "org.servo.servo",
                 "-U",
                 "https://servospeedometer.netlify.app?headless=1",
+                "--ps=--pref",
+                "js_disable_jit=true",
                 "--ps",
                 "--log-filter",
                 "script::dom::console",