perfglue/heap_profiler.cc: expect args as first element on cmd vector

We used to pass 'heap' as the first element of the cmd vector when
handling commands.  We haven't been doing so for a while now, so we
needed to fix this.

Not expecting 'heap' also makes sense, considering that what we need to
know when we reach this function is what command we should handle, and
we should not care what the caller calls us when handling his business.

Fixes: #6361
Backport: dumpling

Signed-off-by: Joao Eduardo Luis <jecluis@gmail.com>
mds: MDS: pass only heap profiler commands instead of the whole cmd vector

The heap profiler doesn't care, nor should it, what our command name is.
It only cares about the commands it handles.

Backport: dumpling

Signed-off-by: Joao Eduardo Luis <jecluis@gmail.com>
osd: OSD: add 'heap' command to known osd commands array

Must have been forgotten during the cli rework.

Backport: dumpling

Signed-off-by: Joao Eduardo Luis <jecluis@gmail.com>
qa: workunits: cephtool: check if 'heap' commands are parseable

Signed-off-by: Joao Eduardo Luis <jecluis@gmail.com>