e2e: accept context from Ginkgo

Every ginkgo callback should return immediately when a timeout occurs or the
test run manually gets aborted with CTRL-C. To do that, they must take a ctx
parameter and pass it through to all code which might block.

This is a first automated step towards that: the additional parameter got added
with

    sed -i 's/\(framework.ConformanceIt\|ginkgo.It\)\(.*\)func() {$/\1\2func(ctx context.Context) {/' \
        $(git grep -l -e framework.ConformanceIt -e ginkgo.It )
    $GOPATH/bin/goimports -w $(git status | grep modified: | sed -e 's/.* //')

log_test.go was left unchanged.

test/e2e_node/node_problem_detector_linux.go

@@ -301,7 +301,7 @@ current-context: local-context
 			hostLogFile = "/var/lib/kubelet/pods/" + string(pod.UID) + "/volumes/kubernetes.io~empty-dir" + logFile
 		})
 
-		ginkgo.It("should generate node condition and events for corresponding errors", func() {
+		ginkgo.It("should generate node condition and events for corresponding errors", func(ctx context.Context) {
 			for _, test := range []struct {
 				description      string
 				timestamp        time.Time