RFR: 8352178: Add precondition in Handshake::execute to prevent deadlock

[Albert Mingkun Yang]

Simple patch of adding `SuspendibleThreadSet` related precondition to `Handshake::execute` in order to prevent deadlock.
All existing callsites satisfy this precondition already.

Test: tier1-5

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Commit messages:
 - handshake-assert

Changes: https://git.openjdk.org/jdk/pull/24088/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24088&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352178
  Stats: 10 lines in 1 file changed: 9 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24088.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24088/head:pull/24088

PR: https://git.openjdk.org/jdk/pull/24088