Disable more stuff for Ubuntu/Debian

Currently, the kernel emits a notice at boot, warning about the usage of
trace_printk(). Disabling samples in efaa3edaaa3b ("Do not build samples
for Debian/Ubuntu") apparently wasn't enough to get rid of that. So
disable more sample and testing stuff that might call this function.

pkg/debian/kernel/ubuntu.config

@@ -5,10 +5,12 @@
 # CONFIG_DEBUG_INFO is not set
 
 ##
-## Do not build samples
+## Do not build samples and tests
 ##
 
 # CONFIG_SAMPLES is not set
+# CONFIG_STM_DUMMY is not set
+# CONFIG_TEST_BPF is not set
 
 ##
 ## Clear out trusted key list as we don't have them.