Only query aurora_version() if aurora postgres extensions are available (#20310)

* Check for aws extensions before querying aurora_version

* Create 20310.fixed

* Minor query tuning

* fix linting error

Author: eric-weaver

postgres/changelog.d/20310.fixed

@@ -0,0 +1 @@
+Check for aws extensions before querying aurora_version()

postgres/datadog_checks/postgres/version_utils.py

@@ -27,7 +27,7 @@
 class VersionUtils(object):
     def __init__(self):
         self.log = get_check_logger()
-        self._seen_aurora_exception = False
+        self._is_aurora = None
 
     @staticmethod
     def get_raw_version(db):
@@ -38,21 +38,29 @@ def get_raw_version(db):
                 return raw_version
 
     def is_aurora(self, db):
-        if self._seen_aurora_exception:
-            return False
+        if self._is_aurora is not None:
+            return self._is_aurora
         with db as conn:
             with conn.cursor(cursor_factory=CommenterCursor) as cursor:
-                # This query will pollute PG logs in non aurora versions,
-                # but is the only reliable way to detect aurora
-                try:
-                    cursor.execute('select AURORA_VERSION();')
-                    return True
-                except Exception as e:
-                    self.log.debug(
-                        "Captured exception %s while determining if the DB is aurora. Assuming is not", str(e)
-                    )
-                    self._seen_aurora_exception = True
-                    return False
+                cursor.execute(
+                    "SELECT 1 FROM pg_available_extension_versions "
+                    "WHERE name ILIKE '%aurora%' OR comment ILIKE '%aurora%' "
+                    "LIMIT 1;"
+                )
+                if cursor.fetchone():
+                    # This query will pollute PG logs in non aurora versions,
+                    # but is the only reliable way to detect aurora.
+                    # Since we found aurora extensions, this should exist.
+                    try:
+                        cursor.execute('select AURORA_VERSION();')
+                        self._is_aurora = True
+                        return self._is_aurora
+                    except Exception as e:
+                        self.log.debug(
+                            "Captured exception %s while determining if the DB is aurora. Assuming is not", str(e)
+                        )
+                self._is_aurora = False
+                return self._is_aurora
 
     @staticmethod
     def parse_version(raw_version):