Remove obsolete comment

mbedtls/mbedtls_config.h (formerly mbedtls/config.h) used to be included
directly in many places, so we wanted to test that all of these places
allowed the MBEDTLS_CONFIG_FILE override. Now mbedtls/mbedtls_config.h is
only included via build_info.h, so this is not relevant anymore.

It is no longer particularly useful to test MBEDTLS_CONFIG_FILE with the
full config, but it isn't harmful either, so keep it that way.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 96189ce..0019757 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -2622,8 +2622,6 @@
 
 component_build_mbedtls_config_file () {
     msg "build: make with MBEDTLS_CONFIG_FILE" # ~40s
-    # Use the full config so as to catch a maximum of places where
-    # the check of MBEDTLS_CONFIG_FILE might be missing.
     scripts/config.py -w full_config.h full
     echo '#error "MBEDTLS_CONFIG_FILE is not working"' >"$CONFIG_H"
     make CFLAGS="-I '$PWD' -DMBEDTLS_CONFIG_FILE='\"full_config.h\"'"