Add the concurrent service sync flag to CCM to match the KCM

[jhorwit2]

What this PR does / why we need it:

The KCM allows changing the number of workers for the service controller, but the CCM does not currently expose that flag. This PR adds the same flag as the KCM to the CCM.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #55560

Release note:

Add the concurrent service sync flag to the Cloud Controller Manager to allow changing the number of workers. (`--concurrent-service-syncs`)

/cc @wlan0 @luxas @thockin

@prydie

[jhorwit2]

/area cloudprovider
/sig cluster-lifecycle

[thockin]

/lgtm
/approve

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jhorwit2, thockin

Associated issue: 55560

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these OWNERS Files:

• cmd/cloud-controller-manager/OWNERS [thockin]

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[k8s-github-robot]

/test all [submit-queue is verifying that this PR is safe to merge]

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 55561, 55519). If you want to cherry-pick this change to another branch, please follow the instructions here.