Refactor: reconciler and eventhandler.

[xuezhaojun]

This PR includes the following changes:

• Remove eventhandler for clustermanagementaddon
• Remove customized eventhandler for managedproxyconfiguration, instead, now use EnqueueRequestForObject.
• Use "managedproxyconfiguration controller" instead of "clustermanagementaddon controller".

[codecov[bot]]

Codecov Report

Patch coverage: 7.14% and project coverage change: -0.81 :warning:

Comparison is base (8dd5b36) 24.12% compared to head (cbc44be) 23.31%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #153 +/- ## ========================================== - Coverage 24.12% 23.31% -0.81% ========================================== Files 9 9 Lines 1202 1175 -27 ========================================== - Hits 290 274 -16 + Misses 896 885 -11 Partials 16 16 ``` | Flag | Coverage Δ | | |---|---|---| | unit | `23.31% <7.14%> (-0.81%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/open-cluster-management-io/cluster-proxy/pull/153?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io) | Coverage Δ | | |---|---|---| | [pkg/config/agent.go](https://codecov.io/gh/open-cluster-management-io/cluster-proxy/pull/153?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io#diff-cGtnL2NvbmZpZy9hZ2VudC5nbw==) | `71.42% <ø> (-28.58%)` | :arrow_down: | | [...ontrollers/managedproxyconfiguration\_controller.go](https://codecov.io/gh/open-cluster-management-io/cluster-proxy/pull/153?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io#diff-cGtnL3Byb3h5c2VydmVyL2NvbnRyb2xsZXJzL21hbmFnZWRwcm94eWNvbmZpZ3VyYXRpb25fY29udHJvbGxlci5nbw==) | `8.56% <7.14%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-cluster-management-io)

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[xuezhaojun]

/assign @qiujian16
/assign @yue9944882

[qiujian16]

/approve /lgtm

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qiujian16, xuezhaojun

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