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/garbage_collector_test.go

@@ -187,7 +187,7 @@ func containerGCTest(f *framework.Framework, test testRun) {
 			}, setupDuration, runtimePollInterval).Should(gomega.BeNil())
 		})
 
-		ginkgo.It(fmt.Sprintf("Should eventually garbage collect containers when we exceed the number of dead containers per container"), func() {
+		ginkgo.It(fmt.Sprintf("Should eventually garbage collect containers when we exceed the number of dead containers per container"), func(ctx context.Context) {
 			totalContainers := 0
 			for _, pod := range test.testPods {
 				totalContainers += pod.numContainers*2 + 1