test: Add missing --v1transport to feature_proxy.py #30531

Fixes #29871

V2 is enabled via:

ci/test/00_setup_env_i686_multiprocess.sh:15:export TEST_RUNNER_EXTRA="--v2transport"

However, that seems premature, given that the test fails intermittently (or reproducibly) on some machines:

$ while test/functional/feature_proxy.py --v2transport --valgrind  ; do true ; done 
2024-07-25T10:09:50.233000Z TestFramework (INFO): PRNG seed is: 4706088440128402104
2024-07-25T10:09:50.234000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test__c5c1wwl
2024-07-25T10:10:16.428000Z TestFramework (ERROR): Assertion failed

AssertionError: not(bytearray(b'node.noumenon') == b'fc00:1:2:3:4:5:6:7')

Fix it by temporarily disabling it.

In the future, the test can be fixed and this can be enabled again.

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utACK fa7010643a44f87e0655e39afba4a455591c72dc

I can try to find out why it's failing with v2, but only next week.

See #30545 for an explanation and a fix within feature_proxy.py.