RFR: 8183348: Better cleanup for jdk/test/sun/security/pkcs12/P12SecretKey.java [v3]

[Mikhail Yankelevich]

> * Changed the test to use scratch directory
> * Cleaned up the imports

Mikhail Yankelevich has updated the pull request incrementally with one additional commit since the last revision:

  changed file format and throwing an exception in case of the failure

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24718/files
  - new: https://git.openjdk.org/jdk/pull/24718/files/44b39103..64d0bd8f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24718&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24718&range=01-02

  Stats: 12 lines in 1 file changed: 7 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/24718.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24718/head:pull/24718

PR: https://git.openjdk.org/jdk/pull/24718