[lldb/Interpreter] Read Scripted Process addressable bits from its metadata (#227515)

This patch addresses post-merge feedback on #224701.

That change added a dedicated `get_addressable_bits` affordance to
scripted processes, which duplicates a property the process already has.
This patch removes it and reads the addressable bits from an optional
"addressable_bits" key in the dictionary returned by
`get_process_metadata` instead. `ScriptedProcess::DidLaunchOrAttach`
still passes the value to `SetAddressableBitMasks` before the first stop
is reported. When the key is missing, the setter is never called and the
process keeps the masks it inherits from the target.

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
GitOrigin-RevId: 257f252ae4476ec709085bc1a033bde1d22d7710