Remove unnecessary LeaseManager unit test.
Remove unnecessary LeaseManager unit test.

Remove the LeaseManagerTest.startUpdaters unit test which did not
really test anything substantial and fails intermittently due to a
time dependency.

RAM-763 #resolve

utah-scs/RAMCloud,SMatsushi/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,utah-scs/RAMCloud,utah-scs/RAMCloud,QingkaiLu/RAMCloud,rstutsman/RAMCloud,matrix207/RAMCloud,alexandermerritt/ramcloud,QingkaiLu/RAMCloud,QingkaiLu/RAMCloud,alexandermerritt/ramcloud,QingkaiLu/RAMCloud,alexandermerritt/ramcloud,anirajk/RAMCloud,matrix207/RAMCloud,SMatsushi/RAMCloud,jblomer/ramcloud,rstutsman/RAMCloud,matrix207/RAMCloud,rstutsman/RAMCloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,rstutsman/RAMCloud,alexandermerritt/ramcloud,jblomer/ramcloud,SMatsushi/RAMCloud,utah-scs/RAMCloud,utah-scs/RAMCloud,jblomer/ramcloud,matrix207/RAMCloud,jblomer/ramcloud,matrix207/RAMCloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,QingkaiLu/RAMCloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,matrix207/RAMCloud,alexandermerritt/ramcloud,utah-scs/RAMCloud,QingkaiLu/RAMCloud,anirajk/RAMCloud,jblomer/ramcloud,jblomer/ramcloud