RFR: 8345079: Simplify/cleanup Exception handling in RMIConnectionImpl

[Kevin Walls]

This is a post-SecurityManager-removal cleanup, following-on from:

8344394: Remove SecurityManager and related calls from java.management.rmi 


Remove mention of "privilege" in Exception handling in RMIConnectionImpl.
Remove wrapping of Exceptions in PrivilegedActionException.

The methods that invoke an operations handle the expected Exceptions, but also need to handle SecurityException and RuntimeException, to avoid their default case of wrapping an Exception in an IOException to signal a problem.

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Commit messages:
 - unnecessary catches
 - (c)
 - 8345079: Simplify/cleanup Exception handling in RMIConnectionImpl

Changes: https://git.openjdk.org/jdk/pull/23072/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23072&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345079
  Stats: 240 lines in 1 file changed: 99 ins; 60 del; 81 mod
  Patch: https://git.openjdk.org/jdk/pull/23072.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23072/head:pull/23072

PR: https://git.openjdk.org/jdk/pull/23072