Debugger: Use different environment variable to override in test

Makes debugging debugger tests easier.

Change-Id: I394862dabfd4f3577b01045b94419b4028ca15ba
Reviewed-by: hjk <hjk121@nokiamail.com>
Debugger: Don't hard code LLDB path on Linux

Change-Id: I7454f710d6ba57e9f6929cbdcfcbf269cf1f43c0
Reviewed-by: hjk <hjk121@nokiamail.com>