CDSPluginTest should only expect classes_nocoops.jsa exists on supported 64-bit platforms

Filed on behalf of Sun Xu (sunxu01@loongson.cn).

The test assumes that it always runs on 64-bit platform and classes_nocoops.jsa is always created.
It's a test bug. The test should only expect classes_nocoops.jsa exists if it's running on a supported 64-bit platform.
However, for unknown target platform, it's unknown if it's 64-bit or not.

This patch fix the test to check if classes_nocoops.jsa exists only on one of the JDK supported platforms (x64 or aarch64) via the sun.arch.data.model system property.