[wifi_cell_test_base] Stop installing pyshark for every wifi job

We can stop installing pyshark etc. as the base image in the lab have
been updated to include them.

BUG=chromium:716556
TEST=test_that chromeos2-row11-rack1-host2.cros network_WiFi_Powersave.wifi_ps
     test_that chromeos2-row11-rack1-host2.cros network_WiFi_GTK
     test_that chromeos2-row11-rack1-host2.cros network_WiFi_Roam.wifi_roamNone
CQ-DEPEND=CL:360690

Change-Id: I1e3309b4612ae5a142e16407b319e67241bbfa36
Reviewed-on: https://chromium-review.googlesource.com/490832
Commit-Ready: Po-Hsien Wang <pwang@chromium.org>
Tested-by: Po-Hsien Wang <pwang@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
diff --git a/server/cros/network/wifi_cell_test_base.py b/server/cros/network/wifi_cell_test_base.py
index 1b5020a..845d13d 100644
--- a/server/cros/network/wifi_cell_test_base.py
+++ b/server/cros/network/wifi_cell_test_base.py
@@ -31,25 +31,7 @@
 
     """
 
-    def _install_pyshark(self):
-        """Installs pyshark and its dependencies for packet capture analysis.
-
-        Uses SSP to install the required pyshark python module and its
-        dependencies including the tshark binary.
-        """
-        logging.info('Installing Pyshark')
-        try:
-            lxc.install_packages(['tshark', 'python-dev', 'libxml2-dev',
-                                  'libxslt-dev', 'zlib1g-dev'],
-                                 ['pyshark'])
-        except error.ContainerError as e:
-            logging.info('Not installing pyshark: %s', e)
-        except error.CmdError as e:
-            raise error.TestError('Error installing pyshark: %s', e)
-
-
     def initialize(self, host):
-        self._install_pyshark()
         if utils.host_could_be_in_afe(host.hostname):
             # There are some DUTs that have different types of wifi modules.
             # In order to generate separate performance graphs, a variant