[lldb] Remove some #ifdef LLDB_CONFIGURATION_DEBUG around asserts

Summary:
Otherwise this code won't run on the Release+Asserts builds we have on the CI.

Fixes rdar://problem/59867885 (partly)

Reviewers: aprantl

Reviewed By: aprantl

Subscribers: JDevlieghere, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D75493