Fix unnecessary header prefixes in tests

Remove unnecessary "../library" prefix from test suite includes. This
makes the tests repo-agnostic between the mbedtls and psa-crypto repos.

Signed-off-by: David Horstmann <david.horstmann@arm.com>

tests/suites/test_suite_common.function

@@ -1,5 +1,5 @@
 /* BEGIN_HEADER */
-#include "../library/common.h"
+#include "common.h"
 
 void fill_arrays(unsigned char *a, unsigned char *b, unsigned char *r1, unsigned char *r2, size_t n)
 {

tests/suites/test_suite_psa_its.function

@@ -10,7 +10,7 @@
  * before changing how test data is constructed or validated.
  */
 
-#include "../library/psa_crypto_its.h"
+#include "psa_crypto_its.h"
 
 #include "test/psa_helpers.h"