[#21585] docdb: Add a tsan suppression for boost::regex_match

Summary:
**Issue:**
Starting from D29217, we changed from std::regex to boost::regex for faster Prometheus metric regex match.
Recently, we observed TSAN race inside of boost::regex_match from many unit tests. This is because saved_state in boost::regex uses a global caches for mem block, and since time period between checking regex was low, TSAN detects race condition.

**Fix:**
Add a tsan suppression as it is a false positive.
Jira: DB-10476

Test Plan: Jenkins

Reviewers: sergei

Reviewed By: sergei

Subscribers: ybase, bogdan

Differential Revision: https://phorge.dev.yugabyte.com/D33355

build-support/tsan-suppressions.txt

@@ -89,6 +89,9 @@ race:yb::ExternalDaemon::LogTailerThread::LogTailerThread
 # Known well implemented lock-free containers
 race:boost::lockfree
 
+# Suppress TSAN data race in boost::regex_match (potential false positive)
+race:boost::regex_detail_500::saved_state::saved_state
+
 # -------------------------------------------------------------------------------------------------
 # Supressions from libcds: