Merge fixes. (#28054)
* Disable expected SILOptimizer test failures.
These tests fail because `-enable-ownership-stripping-after-serialization`
has been disabled for libswiftCore on tensorflow branch due to SR-11336.
TF-799 tracks re-enabling these tests.
* Fix libInMemoryFrontend unittests.
* Remove test/IRGen/copy_value_destroy_value.sil.
The test was deleted upstream in https://github.com/apple/swift/pull/27866.
