Adjust pkgci logging. (#15609)

Before:
https://github.com/openxla/iree/actions/runs/6886652994/job/18732915042#step:7:66
(4000 log lines for timing)
After:
https://github.com/openxla/iree/actions/runs/6884298244/job/18726741906?pr=15609#step:7:67
(250 log lines for timing)
diff --git a/experimental/regression_suite/ireers/fixtures.py b/experimental/regression_suite/ireers/fixtures.py
index 9f9ab77..aa0c9b0 100644
--- a/experimental/regression_suite/ireers/fixtures.py
+++ b/experimental/regression_suite/ireers/fixtures.py
@@ -20,7 +20,7 @@
 
 IREE_COMPILE_QOL_FLAGS = [
     "--mlir-timing",
-    "--mlir-timing-display=tree",
+    "--mlir-timing-display=list",
     "--iree-consteval-jit-debug",
 ]