ut/blob: put setup/clean of tests into common function

A lot of unit tests require only creation of a blobstore
then unload it at the end.
This code can be made common and invoked automatically by
CUnit with CU_add_suite_with_setup_and_teardown().
Those functions are called before and after each test in suite.

This should simplify the unit tests by removing the common
code.

Following patches will add further suites with different
setup/cleanup to reduce common code even more.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Change-Id: I984cde2381f4461e188e06050355024a88ebfca9
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/932


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>