Disable arm64 contracts. (dotnet/coreclr#22605)

Disable arm64 contracts. (dotnet/coreclr#22605)

* Fix ifdef for `g_DbgSuppressAllocationAsserts`.

It needs to be defined under `FEATURE_INTEROP_DEBUGGING`.

* Unify contracts disabling for UNIX/ARM.

It also disables some parts that were disabled for ARM, but not for UNIX.
It fixes the difference that we see between ARM32 and ARM64 Unix Checked.

* Disable contracts on arm64.

FIxes the difference that we see between windows arm32 and arm64 in checked/debug builds.

* Revert CoreFX arm64 timeout change.

That is no longer necessary.

* Reenable arm64 corefx jobs.

They should not fail with timeouts anymore.

* Don't allow `g_DbgSuppressAllocationAsserts` defnition in release builds.

* delete AssertAllocationAllowed

Commit migrated from https://github.com/dotnet/coreclr/commit/6f1bdfffb77ba1c95f46e16a7eeff3cfaf2f2f1f