RFR: 8376300: Avoid more leaks in KeystoreImpl.m because of missing CFRelease calls

[Matthias Baesken]

Seems there is a call to  SecIdentityCopyPrivateKey where we miss calling CFRelease in early returns/failure cases; same for SecIdentityCopyPrivateKey .

See the Apple documentation
https://developer.apple.com/documentation/security/secidentitycopyprivatekey(_:_:)

Also for https://developer.apple.com/documentation/security/secidentitycopycertificate(_:_:)

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Commit messages:
 - JDK-8376300

Changes: https://git.openjdk.org/jdk/pull/29821/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29821&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376300
  Stats: 11 lines in 1 file changed: 10 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29821.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29821/head:pull/29821

PR: https://git.openjdk.org/jdk/pull/29821