RFR: 8271737: Only normalize the cached user.dir property once

[Paul Hohensee]

On Thu, 7 Oct 2021 14:05:19 GMT, Evgeny Astigeevich <duke at openjdk.java.net> wrote:

> The change completes the fix of [JDK-8198997](https://bugs.openjdk.java.net/browse/JDK-8198997) which has added normalisation in a constructor but not removed it from the get method.

Lgtm.

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Marked as reviewed by phh (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5850