Adding operation pruning test (DoS)

Creating n number of operations from same owner. Expecting creation
of all operations should be successful without any error. Whenever all
operation slots are full older operations are expected to be pruned.

Bug: 194359114
Test: atest keystore2_client_test
Change-Id: I9d231658e77cb10f67cfd248072bde0755c1660d
1 file changed