tbb: Skip test_scheduler_mix in ptest

The test hangs intermittently on all architectures and is an open
upstream issue, https://github.com/uxlfoundation/oneTBB/issues/1281.
On qemuarm64 musl it hit the ptest-runner timeout.

AI-Generated: Uses Claude Code
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-oe/recipes-support/tbb/files/run-ptest

@@ -2,7 +2,9 @@
 
 # ctest result lines look like: "  1/142 Test   #1: test_tick_count .....   Passed    0.01 sec"
 # anything other than Passed/Skipped/Disabled (Failed, Timeout, Exception, Not Run) is a FAIL
-ctest | awk '/Test +#[0-9]+:/ {
+# test_scheduler_mix hangs intermittently on every architecture
+# https://github.com/uxlfoundation/oneTBB/issues/1281
+ctest -E '^test_scheduler_mix$' | awk '/Test +#[0-9]+:/ {
     if ($0 ~ /Passed/) res = "PASS"
     else if ($0 ~ /Skipped|Disabled/) res = "SKIP"
     else res = "FAIL"