Fixed glibc issue on linux arm64

[MartinSchmidt]

Had issue when using updated to new library specifically a 'GLIBC_2.33' not found which from previous experience has to do with it being compiled on ubuntu 22:04 since it uses a newer version, regressing to 20.04 should solve the issue.

Also removed some unused crate target.

[xUnit.net 00:00:00.53]     ProjectOrigin.Electricity.IntegrationTests.FlowTests.IssueConsumptionCertificate_Success [FAIL]
  Failed ProjectOrigin.Electricity.IntegrationTests.FlowTests.IssueConsumptionCertificate_Success [97 ms]
  Error Message:
   System.DllNotFoundException : Unable to load shared library 'rust_ffi' or one of its dependencies. In order to help diagnose loading problems, consider using a tool like strace. If you're using glibc, consider setting the LD_DEBUG environment variable: 
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/runtimes/linux-arm64/native/rust_ffi.so: cannot open shared object file: No such file or directory
/usr/share/dotnet/shared/Microsoft.NETCore.App/7.0.5/rust_ffi.so: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/rust_ffi.so: cannot open shared object file: No such file or directory
/lib/aarch64-linux-gnu/libc.so.6: version `GLIBC_2.33' not found (required by /workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/runtimes/linux-arm64/native/librust_ffi.so)
/usr/share/dotnet/shared/Microsoft.NETCore.App/7.0.5/librust_ffi.so: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/librust_ffi.so: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/runtimes/linux-arm64/native/rust_ffi: cannot open shared object file: No such file or directory
/usr/share/dotnet/shared/Microsoft.NETCore.App/7.0.5/rust_ffi: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/rust_ffi: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/runtimes/linux-arm64/native/librust_ffi: cannot open shared object file: No such file or directory
/usr/share/dotnet/shared/Microsoft.NETCore.App/7.0.5/librust_ffi: cannot open shared object file: No such file or directory
/workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/bin/Debug/net7.0/librust_ffi: cannot open shared object file: No such file or directory

  Stack Trace:
     at ProjectOrigin.PedersenCommitment.Ristretto.Scalar.Native.Random()
   at ProjectOrigin.PedersenCommitment.Ristretto.Scalar.Random()
   at ProjectOrigin.PedersenCommitment.SecretCommitmentInfo..ctor(UInt32 message)
   at ProjectOrigin.Electricity.IntegrationTests.FlowTests.IssueConsumptionCertificate_Success() in /workspaces/registry/src/ProjectOrigin.Electricity.IntegrationTests/FlowTests.cs:line 53
--- End of stack trace from previous location ---

[quackzar]

I have actually considered the dependency on glibc for Linux, for which I considered if we should build for musl instead, i.e. statically include libc.
I thought it would be irrelevant, since we are targeting docker images, but it would give compatibility for every linux (x86-64/aarch64) platform.