Fix error handling and log spams in Executor

[eabatalov]

• Generate "customer error" if failed to deserialize graph or function in Initialize RPC.
  ** These errors are not logged as they are in customer owned code.
  ** These errors are added to function's stderr so customer can see them.
• Fix the test for missing module. It didn't check anything because g.run never raises if function fails.
• Use short formatting for exceptions in prod (non-dev) mode so only short backtraces are present in logs without fully rendered local vars in the backtraces and etc. This reduces log spam.
• Revert previous quickfixes that suppress logging of exception details in Executor.

Testing:

make check
make test

Contribution Checklist

• If the python-sdk was changed, please run make fmt in python-sdk/.
• [n/a] If the server was changed, please run make fmt in server/.
• Make sure all PR Checks are passing.