x/build: increase GO_TEST_TIMEOUT_SCALE for freebsd-amd64-race

[findleyr]

While discussing #65845, it came up that GO_TEST_TIMEOUT_SCALE=2 for windows-amd64-race.

Meanwhile, we're having trouble with freebsd-amd64-race timing out in #64473. For most x/tools tests, the freebsd race build is about as slow as the windows race builder, and it's much slower for tests involving significant I/O, such as many of the gopls tests.

Can we increase GO_TEST_TIMEOUT_SCALE for the freebsd builder as well? Is there something better to be done for x/repos? I'd rather increase the timeout than skip tests entirely on this builder, though I'll do the latter if necessary.

[gopherbot]

Change https://go.dev/cl/566055 mentions this issue: dashboard: increase the timeout of freebsd-amd64-race