[release][tune] Remove deprecated SyncConfig usage in tune_cloud_durable release test

[justinvyu]

Why are these changes needed?

#42909 hard deprecated outdated SyncConfig parameters, and this release test was not updated along with the rest of the examples. This syncer parameter was already being ignored, so it's okay to remove it fully now.

Related issue number

Closes #43008

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(