[roll] Roll fuchsia [fuchsia-repo] Use one hyper client per test

These tests have been flaking recently, especially on OS X. It appears
the problem stemmed from how many TCP sockets these tests were using
in parallel. When a TCP connection is closed, the end that initiated the
close falls into a TIME_WAIT state for a period of time before that
local port can be used again to talk to a server. When this happens, any
new connections to that server can get a "Connection Timed Out" error
until a sufficient amount of sockets exit TIME_WAIT.

This test helps to avoid this issue by sharing the same hyper connection
between requests, which allows us to use hyper's connection pooling to
share the same underlying socket.

If this isn't enough to eliminate our flakes, the next step could be to
either add a "retry timed out connections", or to only allow one of
these tests to run at the same time.

Multiply: fuchsia_repo_lib_test: 100
Original-Fixed: 120661
Original-Fixed: 123569
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/825362
Original-Revision: f34b0d9938bc2ecefb43ca3ad3d4934906dbd4d2
GitOrigin-RevId: 54f96d737b26784e69ee975a3edc6aacc35a1e02
Change-Id: I3f6e6e12cd96dd2d0520f31a0ae81e4e3b7519f4