Using outdated cached fuzzer repo.

[DonggeLiu]

Problem

FuzzBench uses a cached fuzzer repo instead of the latest one, which sometimes does not include the new commits required.

Proof of Error

#1902 (comment)

Proposed solution

Removing this.

@jonathanmetzman Would this look good to you?
Those two lines originated from here.
Please let me know if I missed anything (e.g., side-effects of removing them, other preferred solutions), thanks : )