Delete ssl_invasive.h due to duplicated function declarations

All function declaration provided by ssl_invasive.h is needed only for
testing purposes and all of them are provided by constant_time.h as well.

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 83a5e2c..37e8067 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -8,7 +8,7 @@
 #include <mbedtls/debug.h>
 #include <ssl_tls13_keys.h>
 
-#include <ssl_invasive.h>
+#include <constant_time.h>
 
 #include <test/constant_flow.h>