RFR: 8307143: CredentialsCache.cacheName should not be static

Sun Apr 30 13:20:54 UTC 2023

The CC can be loaded with any file and its name is not static.

`MemoryCredentialsCache` is removed since it's not used anywhere. We've already supported native ccache reading directly with JNI method `Credentials::acquireDefaultNativeCreds`.

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Commit messages:
 - the fix

Changes: https://git.openjdk.org/jdk/pull/13737/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13737&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307143
  Stats: 173 lines in 5 files changed: 56 ins; 82 del; 35 mod
  Patch: https://git.openjdk.org/jdk/pull/13737.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13737/head:pull/13737

PR: https://git.openjdk.org/jdk/pull/13737