Fix volume fsType handling for CSI volumes

[ialidzhikov]

How to categorize this PR?

/area storage
/kind bug
/priority normal
/platform openstack

What this PR does / why we need it:
Currently for v1.19 the guestbook test is failing with:

$ k -n gardener-e2e-v2xt6 get po
NAME             READY   STATUS             RESTARTS   AGE
redis-master-0   0/1     CrashLoopBackOff   5          4m13s

$ k -n gardener-e2e-v2xt6 logs redis-master-0
 06:57:52.24 INFO  ==> ** Starting Redis **
1:C 11 Sep 2020 06:57:52.256 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 11 Sep 2020 06:57:52.256 # Redis version=5.0.7, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 11 Sep 2020 06:57:52.256 # Configuration loaded
1:M 11 Sep 2020 06:57:52.257 # Can't open the append-only file: Permission denied

Investigation shows that the fsType is no longer present in the PV spec for v1.19:

Before the fix for PV with k/k v1.19.

   csi:
      driver: cinder.csi.openstack.org
      volumeAttributes:
        storage.kubernetes.io/csiProvisionerIdentity: 1599816861990-1847-cinder.csi.openstack.org
      volumeHandle: 41dc69a8-c853-4b19-b9bd-fb234d6ad618

After the fix:

   csi:
      driver: cinder.csi.openstack.org
      fsType: ext4
      volumeAttributes:
        storage.kubernetes.io/csiProvisionerIdentity: 1599816861990-1847-cinder.csi.openstack.org
      volumeHandle: 41dc69a8-c853-4b19-b9bd-fb234d6ad618

Basically this afterwards is causing the fsGroup field to be not respected when the volume is mounted to the Pod.

For Pod with configured:

  securityContext:
    fsGroup: 1001

Current:

$ cd /data
$ ls -la
total 24
drwxr-xr-x. 3 root root  4096 Sep 11 06:54 .
drwxr-xr-x  1 root root  4096 Sep 11 08:36 ..
drwx------. 2 root root 16384 Sep 11 06:54 lost+found

Expected:

$ cd /data
$ ls -la
total 28
drwxrwsr-x. 3 root 1001  4096 Sep 11 09:09 .
drwxr-xr-x. 1 root root  4096 Sep 11 09:05 ..
-rw-r--r--. 1 1001 1001     0 Sep 11 09:05 appendonly.aof
drwxrws---. 2 root 1001 16384 Sep 11 09:05 lost+found
-rw-r--r--. 1 1001 1001     0 Sep 11 09:09 test.txt

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:
Ref kubernetes-csi/external-provisioner#400

Release note:

An issue causing CSI PV to do not have set `spec.csi.fsType` is now fixed. The csi-provisioner is now started with `--default-fstype=ext4` which is the default fstype to be used when there is no fstype specified in the StorageClass.

[vpnachev]

/lgtm

[ialidzhikov]

$ go test -timeout=0 -mod=vendor ./test/suites/shoot \
      --v -ginkgo.v -ginkgo.progress -ginkgo.noColor \
      --report-file=/tmp/report.json \
      -kubecfg=$KUBECONFIG \
      -shoot-name=$SHOOT_NAME \
      -project-namespace=$PROJECT_NAME \
      -ginkgo.focus="should deploy guestbook app successfully"

• [SLOW TEST:131.334 seconds]
Shoot application testing
/Users/i331370/go/src/github.com/gardener/gardener/test/integration/shoots/applications/shoot_app.go:56
  GuestBook
  /Users/i331370/go/src/github.com/gardener/gardener/test/integration/shoots/applications/shoot_app.go:67
    [DEFAULT] [RELEASE] [SHOOT] should deploy guestbook app successfully
    /Users/i331370/go/src/github.com/gardener/gardener/test/framework/gingko_utils.go:26
------------------------------
S
Ran 1 of 19 Specs in 131.343 seconds
SUCCESS! -- 1 Passed | 0 Failed | 0 Pending | 18 Skipped
--- PASS: TestGardenerSuite (131.35s)
PASS
ok  	github.com/gardener/gardener/test/suites/shoot	132.147s