improve log level of yurthub logs

[rambohe-ch]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line: /kind bug /kind documentation /kind enhancement /kind good-first-issue /kind feature /kind question /kind design /sig ai /sig iot /sig network /sig storage

/kind enhancement

What this PR does / why we need it:

improve log level of yurthub logs because we don't want yurthub to print too many logs.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.1% Duplication on New Code

See analysis details on SonarCloud

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 30.76923% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 55.58%. Comparing base (e4740ba) to head (489131e).

Files	Patch %	Lines
pkg/yurthub/proxy/util/util.go	27.27%	3 Missing and 5 partials :warning:
pkg/yurthub/proxy/remote/loadbalancer.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2055 +/- ## ========================================== - Coverage 55.63% 55.58% -0.05% ========================================== Files 186 186 Lines 18079 18088 +9 ========================================== - Hits 10058 10054 -4 - Misses 6998 7005 +7 - Partials 1023 1029 +6 ``` | [Flag](https://app.codecov.io/gh/openyurtio/openyurt/pull/2055/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/openyurtio/openyurt/pull/2055/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio) | `55.58% <30.76%> (-0.05%)` | :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=openyurtio#carryforward-flags-in-the-pull-request-comment) to find out more.

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