Filter unused authz

[hzxuzhonghu]

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR fixes:
Fixes #1162

Currently istiod does not support pushing only local authorizations.

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov]

Codecov Report

Attention: Patch coverage is 77.27273% with 5 lines in your changes missing coverage. Please review.

Project coverage is 51.88%. Comparing base (ff82786) to head (1230553).
Report is 148 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/controller/workload/workload_processor.go	77.27%	3 Missing and 2 partials ⚠️

Files with missing lines	Coverage Δ
pkg/controller/workload/workload_processor.go	62.07% <77.27%> (+0.93%)	⬆️

... and 9 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6a0def8...1230553. Read the comment docs.

[hzxuzhonghu]

/retest

[LiZhenCheng9527]

nit: Don't you have to check if there are any policies here?
Just like before

[hzxuzhonghu]

not needed

[LiZhenCheng9527]

/lgtm
/approve

[kmesh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: LiZhenCheng9527

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

The pull request process is described here

Needs approval from an approver in each of these files:

• pkg/controller/OWNERS [LiZhenCheng9527]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment