RFR: 8286032: keytool -list -alias should not assume it is always a certificate

[Hai-May Chao]

This fix the warnings of the keytool -list -alias for a secret key that was created with a legacy algorithm.

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Commit messages:
 - 8286032: keytool -list -alias should not assume it is always a certificate

Changes: https://git.openjdk.org/jdk/pull/29250/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29250&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8286032
  Stats: 80 lines in 3 files changed: 71 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/29250.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29250/head:pull/29250

PR: https://git.openjdk.org/jdk/pull/29250