ccl/sqlproxyccl: TestAcceptedConnCountMetric failed

ccl/sqlproxyccl.TestAcceptedConnCountMetric [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/18694191?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/18694191?buildTab=artifacts#/) on release-25.1 @ [3b310111510b3e9bc22472159f344407367f2009](https://github.com/cockroachdb/cockroach/commits/3b310111510b3e9bc22472159f344407367f2009):

```
=== RUN TestAcceptedConnCountMetric
test_log_scope.go:165: test logs captured to: /artifacts/tmp/_tmp/9fd0ddd2a515e470896c2a13882e29c6/logTestAcceptedConnCountMetric3225106318
test_log_scope.go:76: use -show-logs to present logs inline
proxy_handler_test.go:2443:
Error Trace: pkg/ccl/sqlproxyccl/proxy_handler_test.go:2443
Error: Not equal:
expected: 18
actual : 14
Test: TestAcceptedConnCountMetric
panic.go:626: -- test log scope end --
test logs left over in: /artifacts/tmp/_tmp/9fd0ddd2a515e470896c2a13882e29c6/logTestAcceptedConnCountMetric3225106318
--- FAIL: TestAcceptedConnCountMetric (2.46s)
```
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

Same failure on other branches

- #139385 ccl/sqlproxyccl: TestAcceptedConnCountMetric failed [C-test-failure O-robot T-cloud-platform branch-master release-blocker]

/cc @cockroachdb/sql-foundations @cockroachdb/server

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Jira issue: CRDB-47092