Fix debugserver translation check

Currently, debugserver has a test to check if it was launched in
translation. The intent was to cover the case where an x86_64
debugserver attempts to control an arm64/arm64e process, returning
an error. However, this check also covers the case where users
are attaching to an x86_64 process, exiting out before attempting
to hand off control to the translated debugserver at
`/Library/Apple/usr/libexec/oah/debugserver`.

This diff delays the debugserver translation check until after
determining whether to hand off control to
`/Library/Apple/usr/libexec/oah/debugserver`. Only when the
process is not translated and thus has not been handed off do we
check if the debugserver is translated, erroring out in that case.

Reviewed By: jasonmolenda

Differential Revision: https://reviews.llvm.org/D124814