RFR: 8272780: ServerNotifForwarder.removeNotificationListener() incorrect exception handling

[Kevin Walls]

Long-standing nit where an Exception could fail to be reported.
One-character fix to a comparison.
Does not cause any different results in any javax/management tests.

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Commit messages:
 - 8272780: ServerNotifForwarder.removeNotificationListener() incorrect exception handling

Changes: https://git.openjdk.org/jdk/pull/21950/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21950&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8272780
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21950.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21950/head:pull/21950

PR: https://git.openjdk.org/jdk/pull/21950