[lldb] Print message after loading 'crashlog' command

Previously, importing `crashlog` resulted in a message being printed. The
message was about other commands (those in heap.py), not `crashlog`. The
changes in D117237 made it so that the heap.py messages were printed only when
importing `lldb.macosx.heap`, not when importing `lldb.macosx.crashlog`. Some
users may see no output and think `crashlog` wasn't successfully loaded. This
ensures users see that `crashlog` is loaded.

rdar://88283132

Differential Revision: https://reviews.llvm.org/D119155