bootstrap: do not use 'which'
bootstrap: do not use 'which'

Since 'which' command can be absent on some systems by default,
it is easier to test a tool bresence just trying to print its
version only.

Signed-off-by: Kyr Shatskyy <82d0c7561ff7e9a20a19db22e8fb5b2adaa3d71e@suse.com>

ktdreyer/teuthology,ceph/teuthology,ceph/teuthology,ktdreyer/teuthology