src/stirling/obj_tools: bump elf_reader_symbolizer_bpf_test timeout

Last BPF opt (4.14.254) run failed only on this test — TIMEOUT in 180s.
Same treatment as the other BPF tests already bumped on this branch:
default(moderate)→long + flaky=True. The 6.1.106 kernel run passed; this
is the slow-kernel timeout that keeps tripping under qemu-bpf.

Author: entlein

src/stirling/obj_tools/BUILD.bazel

@@ -120,7 +120,9 @@ pl_cc_test(
 
 pl_cc_bpf_test(
     name = "elf_reader_symbolizer_bpf_test",
+    timeout = "long",
     srcs = ["elf_reader_symbolizer_bpf_test.cc"],
+    flaky = True,
     tags = [
         "cpu:16",
         "requires_bpf",