ci: instrument being able to run leaksanitizer (#21142)

tests not in `test/no-validate-leaksan.txt` will run with leaksanitizer
in CI
leaks documented in `test/leaksan.supp` will not cause a test failure

-- notes about leaksanitizer

- will not catch garbage collected objects accumulated during
long-running processes
- will not catch js objects (eg a strong held to a promise)
- will catch native calls to `malloc` not `free`d
- will catch allocations made in C, Zig, C++, libc, dependencies,
dlopen'd

---------

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>

misctools/lldb/init.lldb

@@ -19,3 +19,6 @@ command script import -c bun_pretty_printer.py
 
 command script delete btjs
 command alias btjs p {printf("gathering btjs trace...\n");printf("%s\n", (char*)dumpBtjsTrace())}
+
+# do not pass SIGHUP on to child process. it is often not the real error and the stop point will be nonsensical.
+process handle -p false -s false -n true SIGHUP