RFR: 8330033: com/sun/net/httpserver/bugs/B6431193.java fails in AssertionError after JDK-8326568

[Darragh Clarke]

After integrating [JDK-8326568](https://bugs.openjdk.org/browse/JDK-8326568), B6431193 has been failing due to a suspected race condition on whether the `handlerIsDaemon` is set.

- Moved setting `handlerIsDaemon` from the finally block to before the response is sent

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Commit messages:
 - moved setting boolean to inside try statement to avoid race condition

Changes: https://git.openjdk.org/jdk/pull/18727/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18727&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330033
  Stats: 3 lines in 1 file changed: 1 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18727.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18727/head:pull/18727

PR: https://git.openjdk.org/jdk/pull/18727