test: fix more legacy #include paths

Add a bunch of missing "zephyr/" prefixes to #include statements in
various test and test framework files.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
diff --git a/tests/benchmarks/latency_measure/src/utils.h b/tests/benchmarks/latency_measure/src/utils.h
index 9bff41e..e68ee3b 100644
--- a/tests/benchmarks/latency_measure/src/utils.h
+++ b/tests/benchmarks/latency_measure/src/utils.h
@@ -14,7 +14,7 @@
 #include <zephyr/timing/timing.h>
 #include <zephyr/sys/printk.h>
 #include <stdio.h>
-#include "timestamp.h"
+#include <zephyr/timestamp.h>
 
 #define INT_IMM8_OFFSET   1
 #define IRQ_PRIORITY      3