RFR: 8371471: HttpClient: Log HTTP/3 handshake failures if logging errors is enabled

[Daniel Fuchs]

Surprisingly if the QUIC handshake fails exceptionally, and `-Djdk.httpclient.HttpClient.log=errors` is specified, the exception is not logged. This change fixes that.

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Commit messages:
 - 8371471: HttpClient: Log HTTP/3 handshake failures if logging errors is enabled

Changes: https://git.openjdk.org/jdk/pull/28196/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28196&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371471
  Stats: 185 lines in 3 files changed: 183 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28196.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28196/head:pull/28196

PR: https://git.openjdk.org/jdk/pull/28196