Prevent clusterDefaultNodeSelector label from being added on opening of edit cluster dialog

[Waseem826]

What this PR does / why we need it:
Prevent clusterDefaultNodeSelector label from being added on opening of edit cluster dialog if those labels are not present in cluster object.

Which issue(s) this PR fixes:

Fixes #5979

What type of PR is this?

/kind bug
Special notes for your reviewer:

Does this PR introduce a user-facing change? Then add your Release Note here:

Fix an issue where `clusterDefaultNodeSelector` label was being added back on opening of edit cluster dialog.

Documentation:

NONE

[Waseem826]

/cherrypick release/v2.23

[kubermatic-bot]

@Waseem826: once the present PR merges, I will cherry-pick it on top of release/v2.23 in a new PR and assign it to you.

In response to this:

/cherrypick release/v2.23

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[Waseem826]

/cherrypick release/v2.22

[kubermatic-bot]

@Waseem826: once the present PR merges, I will cherry-pick it on top of release/v2.22 in a new PR and assign it to you.

In response to this:

/cherrypick release/v2.22

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[ahmadhamzh]

/lgtm
/approve

[kubermatic-bot]

LGTM label has been added.

Git tree hash: c486ca5a7e9963d17b527d439b4ec38de539f902

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahmadhamzh

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[kubermatic-bot]

@Waseem826: new pull request created: #6368

In response to this:

/cherrypick release/v2.23

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[kubermatic-bot]

@Waseem826: new pull request created: #6369

In response to this:

/cherrypick release/v2.22

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.