[YSQL] ysql connection manager `TestStatsAndMetrics ` test is flaky

[druzac]

Jira Link: DB-19251

Description

The test org.yb.ysqlconnmgr.TestStatsAndMetrics.testControlPoolConnections has been flaky for some time. A recent diff #28670 made it flakier.

Issue Type

kind/failing-test

Warning: Please confirm that this issue does not contain any sensitive information

• I confirm this issue does not contain any sensitive information.