The proxy must be waiting for the etcd to be running, but the current
implementation hard codes the wating time as 5 seconds. The improvement
is to dynamically check whether the etcd is running, and start the
proxy when etcd port is reachable.
Signed-off-by: Benjamin Wang <wachao@vmware.com>
Before:
```
{"level":"info","ts":1610273495.3791487,"caller":"agent/handler.go:668","msg":"cleaning up page cache"}
{"level":"info","ts":1610273495.3793094,"caller":"agent/handler.go:94","msg":"created etcd log file","path":"/tmp/etcd-functional-2/etcd.log"}
{"level":"info","ts":1610273495.379328,"caller":"agent/handler.go:668","msg":"cleaning up page cache"}
[sudo] password for ptab:
pam_glogin: invalid password
Sorry, try again.
[sudo] password for ptab:
```
Now the caches are dropped if the current users is in sudoers, bot not
in the other cases.
To be honest I don't see the purpose for dropping the caches at all in
the test.
