Option to set TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES

Option to set TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES

Use "ceph_tcmalloc_max_total_thread_cache" to set the
TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES value inside /etc/default/ceph for
Debian installs, or /etc/sysconfig/ceph for Red Hat/CentOS installs.

By default this is set to 0, so the default package value will be used,
if specified this value will be changed to match the variable, and ceph
osd services will be restarted.

(cherry picked from commit 7f6c39102d4fc1c9ec987fe3dd06693a94ad56fb)
Signed-off-by: Sébastien Han <seb@redhat.com>