sp_HumanEvents: restore 1/0 idiom in CATCH session-existence EXISTS checks

PR #808 changed SELECT 1/0 to SELECT 1 in the two EXISTS checks on a
reviewer suggestion, but the SELECT list inside EXISTS is never evaluated,
so there is no divide-by-zero risk. 1/0 is the house style for EXISTS in
this codebase; revert both checks to it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

sp_HumanEvents/sp_HumanEvents.sql

@@ -5022,7 +5022,7 @@ BEGIN CATCH
                                     WHEN EXISTS
                                          (
                                              SELECT
-                                                 1
+                                                 1/0
                                              FROM sys.server_event_sessions AS ses
                                              WHERE ses.name = @session_name
                                          )
@@ -5038,7 +5038,7 @@ BEGIN CATCH
                                     WHEN EXISTS
                                          (
                                              SELECT
-                                                 1
+                                                 1/0
                                              FROM sys.database_event_sessions AS ses
                                              WHERE ses.name = @session_name
                                          )