RFR: 8344205: [PPC]: failing assertion: sharedRuntime_ppc.cpp:1652: cookie not found

[Richard Reingruber]

This PR removes the bad assertion that fails when leaving a continuation because the cookie value is not found in `frame::common_abi::cr`.
This is because after the cookie is stored there when entering the continuation it is overridden by the runtime call to thaw frames. This is compliant with the abi.
Strangely the assertion only ever failed on aix.

Testing: compiler/codecache/stress/UnexpectedDeoptimizationTest.java always failed since the bad assertion was introduced recently. It succeeds after removal.

The fix passed our CI testing:
Tier 1-4 of hotspot and jdk. All of Langtools and jaxp. Renaissance Suite and SAP specific tests.
Testing was done on the main platforms and also on Linux/PPC64le and AIX.

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Commit messages:
 - Remove bad assertion

Changes: https://git.openjdk.org/jdk/pull/22109/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22109&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344205
  Stats: 5 lines in 1 file changed: 0 ins; 5 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22109.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22109/head:pull/22109

PR: https://git.openjdk.org/jdk/pull/22109