test: move flaky performance vinyl/throttle.test.lua test to separate mode run

[avtikhon]

Tarantool version:
All

OS version:
All

Bug description:
Disabled vinyl/throttle.test.lua test due to performance
test need to be reorganized into separate mode at the standalone
host. Currently this test doesn't show any issue, but breaks the
testing some time, with errors like:

[029] --- vinyl/throttle.result Wed Apr 17 08:01:27 2019
[029] +++ vinyl/throttle.reject Wed Apr 17 08:03:08 2019
[029] @@ -86,7 +86,7 @@
[029] ...
[029] latency < 0.2 or latency
[029] ---
[029] -- true
[029] +- 0.23262786865234
[029] ...
[029] test_run:cmd('switch default')
[029] ---
[029]

next run produced:
[014] +- 1.5368704795837

To make the vinyl suite possible run in parallel decided to disable
the current test temporary till the special performance group will
be available and it will be moved there.

Steps to reproduce:
./test-run.py -j 50 --force --long vinyl/

Optional (but very desirable):

• coredump
• backtrace
• netstat