Summary:
There are a lot of failing RPCs because of timeout in TSAN mode.
It increase total number of RPCs causing test to fail.

Added logic to ignore failed calls.
Jira: DB-14287

Test Plan: ./yb_build.sh tsan --gtest_filter PgLibPqTest.NumberOfInitialRpcs -n 4

Reviewers: dmitry

Reviewed By: dmitry

Subscribers: ybase, yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D40383