Revert "Updated tests to build webpack before python tests"

This reverts commit 7d93b5c.

docker/run.sh

@@ -55,7 +55,9 @@ function setup {
             -dname 'CN=Foo, OU=Bar, O=Bizzle, L=Bazzle, ST=Bingle, C=US'
     fi
 
-    yarn install --progress=false --frozen-lockfile
+    if [ "$TEST" = "javascript" -o "$JS_SETUP" = "yes" ]; then
+        yarn install --progress=false --frozen-lockfile
+    fi
 }
 
 function python_preheat {
@@ -130,16 +132,15 @@ function run_tests {
 
         send_timing_metric_to_datadog "setup" $delta
 
-        logmsg INFO "Building Webpack"
-        chown -R cchq:cchq ./webpack
-        su cchq -c "yarn build"
-
         log_group_begin "Django test suite: $TEST"
         now=$(date +%s)
         argv_str=$(printf ' %q' "$TEST" "$@")
         su cchq -c "/bin/bash ../run_tests $argv_str" 2>&1
         log_group_end  # only log group end on success (notice: `set -e`)
         if [ "$TEST" == "python-sharded-and-javascript" ]; then
+            logmsg INFO "Building Webpack"
+            chown -R cchq:cchq ./webpack
+            su cchq -c "yarn build"
             su cchq -c scripts/test-prod-entrypoints.sh
             scripts/test-make-requirements.sh
             scripts/test-serializer-pickle-files.sh