Remove unneeded kubelet binary check in bootstrapping

* binary check is not needed in GKE as this is old (unused) code
  that comes from when kubernetes was forked
* remove TEST_CLUSTER functionality
* adds unnecessary .5 seconds to bootstrapping latency

Verification:
* ensured bootstrapping successfully configures node using custom
  k8s version

BUG=389110387
Change-Id: I5d311ffea0e3b02c01debe7291eb630669391bde

Author: ollyplance

gke/cluster/gce/gci/configure-helper.sh

@@ -1686,22 +1686,6 @@ function start-kubelet {
   echo "Start kubelet"
 
   local kubelet_bin="${KUBE_HOME}/bin/kubelet"
-  local -r version="$("${kubelet_bin}" --version=true | cut -f2 -d " ")"
-  local -r builtin_kubelet="/usr/bin/kubelet"
-  if [[ "${TEST_CLUSTER:-}" == "true" ]]; then
-    # Determine which binary to use on test clusters. We use the built-in
-    # version only if the downloaded version is the same as the built-in
-    # version. This allows GCI to run some of the e2e tests to qualify the
-    # built-in kubelet.
-    if [[ -x "${builtin_kubelet}" ]]; then
-      local -r builtin_version="$("${builtin_kubelet}"  --version=true | cut -f2 -d " ")"
-      if [[ "${builtin_version}" == "${version}" ]]; then
-        kubelet_bin="${builtin_kubelet}"
-      fi
-    fi
-  fi
-  echo "Using kubelet binary at ${kubelet_bin}"
-
   local -r kubelet_env_file="/etc/default/kubelet"
 
   local kubelet_cgroup_driver=""

gke/cluster/gce/windows/common.psm1

@@ -633,21 +633,6 @@ Rotate-Files -Pattern '${Pattern}' -Path '${Path}' -Config `$config
   }
 }
 
-# Returns true if this node is part of a test cluster (see
-# cluster/gce/config-test.sh). $KubeEnv is a hash table containing the kube-env
-# metadata keys+values.
-function Test-IsTestCluster {
-  param (
-    [parameter(Mandatory=$true)] [hashtable]$KubeEnv
-  )
-
-  if ($KubeEnv.Contains('TEST_CLUSTER') -and `
-      ($KubeEnv['TEST_CLUSTER'] -eq 'true')) {
-    return $true
-  }
-  return $false
-}
-
 # Returns true if this node uses a plugin to support authentication to the
 # master, e.g. for TPM-based authentication. $KubeEnv is a hash table
 # containing the kube-env metadata keys+values.