ART: Use signal_dumper in run-test by default

Be hermetic and ensure best dump results (dex integration etc) by
defaulting to timeout over gdb.

Bug: 134837513
Test: m test-art-host
Change-Id: Ie8f623fb1d71d665eb8038a7dfa7f95849a8ba84
diff --git a/test/etc/run-test-jar b/test/etc/run-test-jar
index 85e41c3..e99d240 100755
--- a/test/etc/run-test-jar
+++ b/test/etc/run-test-jar
@@ -55,7 +55,7 @@
 RELOCATE="n"
 STRIP_DEX="n"
 SECONDARY_DEX=""
-TIME_OUT="gdb"  # "n" (disabled), "timeout" (use timeout), "gdb" (use gdb)
+TIME_OUT="timeout"  # "n" (disabled), "timeout" (use timeout), "gdb" (use gdb)
 TIMEOUT_DUMPER=signal_dumper
 # Value in seconds
 if [ "$ART_USE_READ_BARRIER" != "false" ]; then