ci: run ipc functional tests in arm job #35466

These are currently skipped, because pycapnp isn't installed (https://github.com/bitcoin/bitcoin/actions/runs/26943765833/job/79499532298#step:10:4286):

interface_ipc.py                                                                 | ○ Skipped | 0 s
interface_ipc_mining.py                                                          | ○ Skipped | 0 s

They seem to work fine locally. Not sure if this was missed, or on purpose.

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35466.

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ACK b2fbd5b5ddafb7ad4dd2f8b4dddd637974cedf5e

ACK b2fbd5b5ddafb7ad4dd2f8b4dddd637974cedf5e

The 32 bit ARM job now shows:

interface_ipc.py                                                                 | ✓ Passed  | 1 s
interface_ipc_cli.py                                                             | ✓ Passed  | 0 s
interface_ipc_mining.py                                                          | ✓ Passed  | 133 s

It wasn't added in #33201 because RUN_FUNCTIONAL_TESTS was false at the time. They were turned on in #34136 a few months later:

Also, enable the functional tests in 32-bit CI, to confirm the regression test.