[gtest] Consume AssertionResults in system_trust_store_nss...cc

`ASSERT_NO_FATAL_FAILURE(...)` checks for `ASSERT_*` failures while
executing the provided statement [0] but discards any expression. Use a
plain `ASSERT_TRUE()` to actually check that `ParseX509Certificate()`
succeeds.

The dropped assertion causes a build failure [1] with a recent
Googletest revision that marks `AssertionResult` as `[[nodiscard]]` [2].

[0]: https://google.github.io/googletest/advanced.html#asserting-on-subroutines
[1]: https://ci.chromium.org/ui/p/chromium/builders/try/chromeos-amd64-generic-rel-gtest/374803/overview
[2]: 3fbe4db9a3%5E%21/

Bug: 398298306
Change-Id: I809e26995510d4055d8aa9282be377cb86b34455
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6299635
Commit-Queue: Matt Mueller <mattm@chromium.org>
Reviewed-by: Matt Mueller <mattm@chromium.org>
Auto-Submit: Jonathan Lee <jonathanjlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1424797}

net/cert/internal/system_trust_store_nss_unittest.cc

@@ -31,7 +31,7 @@ namespace net {
 namespace {
 
 // Parses |x509_cert| as a bssl::ParsedCertificate and stores the output in
-// *|out_parsed_cert|. Wrap in ASSERT_NO_FATAL_FAILURE on callsites.
+// *|out_parsed_cert|.
 ::testing::AssertionResult ParseX509Certificate(
     const scoped_refptr<X509Certificate>& x509_cert,
     std::shared_ptr<const bssl::ParsedCertificate>* out_parsed_cert) {
@@ -62,8 +62,7 @@ class SystemTrustStoreNSSTest : public ::testing::Test {
     root_cert_ =
         ImportCertFromFile(GetTestCertsDirectory(), "root_ca_cert.pem");
     ASSERT_TRUE(root_cert_);
-    ASSERT_NO_FATAL_FAILURE(
-        ParseX509Certificate(root_cert_, &parsed_root_cert_));
+    ASSERT_TRUE(ParseX509Certificate(root_cert_, &parsed_root_cert_));
     nss_root_cert_ =
         x509_util::CreateCERTCertificateFromX509Certificate(root_cert_.get());
     ASSERT_TRUE(nss_root_cert_);