explicitly set default AZURE_SYNC_PERIOD for ASO

[nojnhuh]

What type of PR is this?
/kind bug

What this PR does / why we need it:

It looks like when we specify AZURE_SYNC_PERIOD: "" in the aso-controller-settings Secret, ASO is interpreting that as "do not resync" instead of "use the 1h default" like the docs describe and what we originally intended: https://azure.github.io/azure-service-operator/guide/aso-controller-settings-options/#azure_sync_period. This behavior might be a bug in ASO (Azure/azure-service-operator#3965), in which case this PR is a workaround. If this is intended behavior in ASO, then this PR represents a fix on our side.

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

Special notes for your reviewer:

• cherry-pick candidate

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

[`AZURE_SYNC_PERIOD`](https://azure.github.io/azure-service-operator/guide/aso-controller-settings-options/#azure_sync_period) for ASO now defaults to `1h` instead of "effectively never"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.38%. Comparing base (3d9f761) to head (e720de6).
Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4764      +/-   ##
==========================================
- Coverage   62.47%   62.38%   -0.09%     
==========================================
  Files         195      196       +1     
  Lines       15902    16088     +186     
==========================================
+ Hits         9934    10037     +103     
- Misses       5268     5325      +57     
- Partials      700      726      +26     

☔ View full report in Codecov by Sentry.
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[mboersma]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 1bf9862dc5d36f7c55403a87c71824baf44409d4

[willie-yao]

/lgtm

[mboersma]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mboersma

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[nojnhuh]

/cherry-pick release-1.13

[nojnhuh]

/cherry-pick release-1.14

[k8s-infra-cherrypick-robot]

@nojnhuh: new pull request created: #4782

In response to this:

/cherry-pick release-1.13

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.

[k8s-infra-cherrypick-robot]

@nojnhuh: new pull request created: #4783

In response to this:

/cherry-pick release-1.14

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.