rgw/cache: this commit squashes commits for removing CephContext* from

rgw/cache: this commit squashes commits for removing CephContext* from
ssd, redis driver and related test files.

rgw/cache: removing CephContext* from ssd driver and redis driver.
It can be accessed in every api using dpp->get_cct(), where dpp
is of type DoutPrefixProvider*.
rgw/test: Remove `cct` parameter from cache driver initialization call
redis driver test file.
rgw/qa: removing cct parameter from ssd driver test file.

Signed-off-by: Pritha Srivastava <prsrivas@redhat.com>
Signed-off-by: Samarah <samarah.uriarte@ibm.com>