Revert "Adjusts the USAP pool refill mechanism."

This reverts commit 0779af6259a1aa595a010648ddaf96470a0458b1.

Reason for revert: Breaks cts SignedConfigHostTest

Note: This CL effectively reverts commit:
54b8d7ea4da61a5a2bf08c8701f41b2d58e360e3
"Make the USAP Pool refill delay configurable."

As that builds on top of the original CL being reverted. Only the
ZygoteServer portion of that change is reverted.

Test: atest SignedConfigHostTest
(on an acloud instance)
Bug: 132794985
Merged-In: I1327a22d103452bed46d191ec2bafb72a5e095ca
Change-Id: I1327a22d103452bed46d191ec2bafb72a5e095ca
5 files changed