When a unary request takes more than predefined duration, this request
is defined as "expensive" and a warning is printed. The expensive request
duration is hard-coded to 300 ms. It can be not enough for example
for transactions with a lot of operations. The warnings just blow up
the log files and reduce throughput.
This fix allows user to configure the "expensive" request duration.
Signed-off-by: Alexey Roytman <roytman@il.ibm.com>
Flags `--experimental-enable-v2v3` and '-enable-v2' will raise a warning in 3.5,
in 3.6 they are schedule for decomissioning, such that v2store can stop be written in 3.7.
Deprecation plan in: https://github.com/etcd-io/etcd/issues/12913
