selftests: drv-net: Strip '@' prefix from bpftrace map keys

The '@' prefix in bpftrace map keys is specific to bpftrace and can be
safely removed when processing results. This patch modifies the bpftrace
utility to strip the '@' from map keys before storing them in the result
dictionary, making the keys more consistent with Python conventions.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250714-netpoll_test-v7-2-c0220cfaa63e@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/lib/py/utils.py

@@ -217,6 +217,8 @@ def bpftrace(expr, json=None, ns=None, host=None, timeout=None):
             if one.get('type') != 'map':
                 continue
             for k, v in one["data"].items():
+                if k.startswith('@'):
+                    k = k.lstrip('@')
                 ret[k] = v
         return ret
     return cmd_obj