btrfs: set default discard iops_limit to 1000

Previously, the default was a relatively conservative 10. This results
in a 100ms delay, so with ~300 discards in a commit, it takes the full
30s till the next commit to finish the discards. On a workstation, this
results in the disk never going idle, wasting power/battery, etc.

Set the default to 1000, which results in using the smallest possible
delay, currently, which is 1ms. This has shown to not pathologically
keep the disk busy by the original reporter.

Link: https://lore.kernel.org/linux-btrfs/Y%2F+n1wS%2F4XAH7X1p@nz/
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2182228


CC: stable@vger.kernel.org # 6.2+
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>