revert an accidental test code change done as part of the tls project
revert an accidental test code change done as part of the tls project

it seems that commit b087dd1db60ed23d9e59304deb0b1599437f6e23 accidentially changed
gen_write_load to not use deferred client, which causes them to be slower and not
generate high load which they should, making some tests less effecitive

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis