RFR: 8360178: TestArguments.atojulong gtest has incorrect format string

[Kim Barrett]

Please review this fix for the format directive when printing ULLONG_MAX by
TestArguments.atojulong gtest. Instead of using JULONG_FORMAT, which might not
be the proper type (though sized properly), use "%llu" to avoid potential
warning.

Also changed the test_arguments.cpp file to use os::snprintf instead of
jio_snprintf, and improved checking the results of those calls.

Testing: mach5 tier1

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Commit messages:
 - fix test_arguments.cpp

Changes: https://git.openjdk.org/jdk/pull/25927/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25927&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8360178
  Stats: 11 lines in 1 file changed: 4 ins; 2 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/25927.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25927/head:pull/25927

PR: https://git.openjdk.org/jdk/pull/25927