MB-12537: Remove no longer used performance scripts

The performance scripts in testrunner got replaced by perfrunner [1].

[1]: https://github.com/couchbaselabs/perfrunner

Change-Id: I2c956441f3d2e1d4342e28eb189636dd457e05df
Reviewed-on: http://review.couchbase.org/42847
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Thomas Anderson <tja.j08@gmail.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>