[lldb] Update custom commands to always be overrriden

This is a follow-up patch to 6f7835f309b9.

As explained previously, when running from an IDE, it can happen that
the IDE imports some lldb scripts by itself. If the user also tries to
import these commands, lldb will show the following message:

```
error: cannot add command: user command exists and force replace not set
```

This message is confusing to the user, because it suggests that the
command import failed and that the execution should stop. However, in
this case, lldb will continue the execution with the command added
previously by the user.

To prevent that, this patch updates every first-party lldb-packaged
custom commands to override commands that were pre-imported in lldb.

Differential Revision: https://reviews.llvm.org/D140293



Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>