test: force client-side watching
test: force client-side watching

The direct reason for this is to fix CI on windows, which seems to fail
for some reason after we fixed the watcher-selection logic which (I
think) changed the tests behavior to use notify rather than client.

But this patch seems to make sense in general -- file watching is
notoriously finicky, so controlling it explicitly leads to less fragile
tests.

rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer