Fix StatefulSet Pod creation for caches with a long upstream

[ialidzhikov]

How to categorize this PR?

/area quality
/kind bug

What this PR does / why we need it:
The reason for #120 is kubernetes/kubernetes#64023. Long story short the explanation is:

	// The StatefulSet name limit is 63 chars. However Pods for a StatefulSet with name > 52 chars cannot be created due to https://github.com/kubernetes/kubernetes/issues/64023.
	// The "controller-revision-hash" label gets added to the StatefulSet Pod. The label value is in format <stateful_set_name>_<hash> where <hash> is 10 or 11 chars.

With this PR we mitigate the upstream issue by NOT exceeding 52 chars for StatefulSet names. This change should be backwards-compatible.

Which issue(s) this PR fixes:
Fixes #120

Special notes for your reviewer:
For completeness, these are some size limits in K8s:

• StatefulSet name length - 63, https://github.com/kubernetes/kubernetes/blob/a714e9e4855f93053206555f5810f6942acb7a8d/pkg/apis/apps/validation/validation.go#L39-L44
• Pod name length - 253, https://github.com/kubernetes/kubernetes/blob/703edddae4e3d5bb655742afffc0a757103a2526/pkg/apis/core/validation/validation.go#L244
• Pod label value length - 63, https://github.com/kubernetes/kubernetes/blob/703edddae4e3d5bb655742afffc0a757103a2526/pkg/apis/core/validation/validation.go#L244
• Secret name length - 253, https://github.com/kubernetes/kubernetes/blob/703edddae4e3d5bb655742afffc0a757103a2526/pkg/apis/core/validation/validation.go#L281
• PVC name length - 253, https://github.com/kubernetes/kubernetes/blob/703edddae4e3d5bb655742afffc0a757103a2526/pkg/apis/core/validation/validation.go#L1661

Release note:

An issue causing the registry StatefulSet to fail to create Pods for registry caches with long upstreams is now mitigated.

[gardener-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[dimitar-kostadinov]

/lgtm
Minor nits inline

[gardener-prow]

LGTM label has been added.

Git tree hash: b3ebb90425b6276216bbe903299d5a97b48da785

[dimitar-kostadinov]

/lgtm

[gardener-prow]

LGTM label has been added.

Git tree hash: 3407fdd6267e9d1f11708714325cf3887008e9f2

[ialidzhikov]

/approve

[gardener-prow]

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