Improve logger Pause handling

[wxiaoguang]

The old EventWriter's Run does:

for {
    handlePause()
    select {
    case event <- Queue:
         write the log event ...
    }
}

So, if an event writer is started before the logger is paused, there is a chance that the logger isn't paused for the first message.

The new logic is:

for {
    select {
    case event <- Queue:
         handlePause()
         write the log event ...
    }
}

Then the event writer can be correctly paused

[wxiaoguang]

Last CI failure is still related to pin issue:

 --- FAIL: TestAPIListPinnedIssues (1.58s)
    testlogger.go:60: 2023/05/26 13:44:33 ...les/storage/local.go:47:NewLocalStorage() [I] Creating new Local Storage at /home/runner/work/gitea/gitea/tests/gitea-lfs-meta
    testlogger.go:60: 2023/05/26 13:44:33 ...eb/routing/logger.go:102:func1() [I] router: completed GET /user/login for test-mock:12345, 200 OK in 7.9ms @ auth/auth.go:141(auth.SignIn)
    testlogger.go:60: 2023/05/26 13:44:33 ...eb/routing/logger.go:102:func1() [I] router: completed POST /user/login for test-mock:12345, 303 See Other in 9.8ms @ auth/auth.go:170(auth.SignInPost)
    testlogger.go:60: 2023/05/26 13:44:34 ...eb/routing/logger.go:102:func1() [I] router: completed GET /user/settings/applications for test-mock:12345, 200 OK in 20.6ms @ setting/applications.go:23(setting.Applications)
    testlogger.go:60: 2023/05/26 13:44:34 ...eb/routing/logger.go:102:func1() [I] router: completed POST /user/settings/applications for test-mock:12345, 303 See Other in 126.1ms @ setting/applications.go:33(setting.ApplicationsPost)
    testlogger.go:60: 2023/05/26 13:44:34 ...eb/routing/logger.go:102:func1() [I] router: completed GET /user/settings/applications for test-mock:12345, 200 OK in 22.7ms @ setting/applications.go:23(setting.Applications)
    testlogger.go:60: 2023/05/26 13:44:34 ...eb/routing/logger.go:102:func1() [I] router: completed POST /api/v1/repos/user2/repo1/issues/2/pin?token=a36803b2e14811c9a8fffed3cbd319d55cf7963e for test-mock:12345, 204 No Content in 131.2ms @ repo/issue_pin.go:16(repo.PinIssue)
    testlogger.go:60: 2023/05/26 13:44:34 ...eb/routing/logger.go:102:func1() [I] router: completed GET /api/v1/repos/user2/repo1/issues/pinned for test-mock:12345, 200 OK in 7.9ms @ repo/issue_pin.go:175(repo.ListPinnedIssues)
    api_issue_pin_test.go:170: 
        	Error Trace:	/home/runner/work/gitea/gitea/tests/integration/api_issue_pin_test.go:170
        	Error:      	Not equal: 
        	            	expected: 1
        	            	actual  : 0
        	Test:       	TestAPIListPinnedIssues
panic: runtime error: index out of range [0] with length 0 [recovered]
	panic: runtime error: index out of range [0] with length 0

goroutine 24092 [running]:
testing.tRunner.func1.2({0x45fb980, 0xc00218d968})
	/opt/hostedtoolcache/go/1.20.4/x64/src/testing/testing.go:1526 +0x372
testing.tRunner.func1()
	/opt/hostedtoolcache/go/1.20.4/x64/src/testing/testing.go:1529 +0x650
panic({0x45fb980, 0xc00218d968})
	/opt/hostedtoolcache/go/1.20.4/x64/src/runtime/panic.go:890 +0x263
code.gitea.io/gitea/tests/integration.TestAPIListPinnedIssues(0x0?)
	/home/runner/work/gitea/gitea/tests/integration/api_issue_pin_test.go:171 +0x799
testing.tRunner(0xc0486c01a0, 0x4c93198)
	/opt/hostedtoolcache/go/1.20.4/x64/src/testing/testing.go:1576 +0x217
created by testing.(*T).Run
	/opt/hostedtoolcache/go/1.20.4/x64/src/testing/testing.go:1629 +0x806
make[1]: *** [/home/runner/work/gitea/gitea/Makefile:572: test-pgsql] Error 2
make: *** [Makefile:8: test-pgsql] Error 2
Error: Process completed with exit code 2.