[Process] Fix process status in TTY mode

When running a process with TTY mode, status in automatically set to `terminated`
once it's started.

It's wrong for two reasons :
 - The status of the process is not yet terminated.
 - The exitcode value is never caught
bug #10412 [Process] Fix process status in TTY mode (romainneutron)

This PR was merged into the 2.3 branch.

Discussion
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[Process] Fix process status in TTY mode

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

When running a process with TTY mode, status in automatically set to `terminated`
once it's started.

It's wrong for two reasons :
 - The status of the process is not yet terminated.
 - The exitcode value is never caught

Commits
-------

51c70f8 [Process] Fix process status in TTY mode
[Process] Make process tests more accurate on exception messages