RFR: 8344134: Use static property in SystemLookup

[Per Minborg]

This PR proposes to use a static property already resolved instead of calling `System.getProperty()`.

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Commit messages:
 - Use StaticProperty.javaHome()

Changes: https://git.openjdk.org/jdk/pull/22205/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22205&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344134
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22205.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22205/head:pull/22205

PR: https://git.openjdk.org/jdk/pull/22205