tests: add xfail-strict reproducer for funder-side stuck CHANNELD_AWAITING_LOCKIN

[ksedgwic]

When a node is the funder of a channel whose funding tx never confirms (broadcast rejected at ATMP, evicted from mempool, or simply never broadcast), the channel record stays in CHANNELD_AWAITING_LOCKIN indefinitely. CLN already implements the BOLT 2 fundee-side forget rule (PR #1468, --max-funding-unconfirmed-blocks, default 2016) but has no equivalent on the funder side.

The test asserts the desired post-fix behavior (state has moved beyond CHANNELD_AWAITING_LOCKIN) and is marked @pytest.mark.xfail(strict=True) so:

• CI reports XFAIL today (acceptable; documents the open bug)
• When the bug is fixed, the test reports XPASS, which strict=True promotes to a hard failure to alert the dev to remove the marker.

Reproduces #9112

[ksedgwic]

Adds a second xfail-strict reproducer for the same root cause:
test_funder_stuck_close_before_funding_confirm.

If the operator (or an automation like CLBOSS's spenderp) issues
close while the funder is in CHANNELD_AWAITING_LOCKIN with an
unbroadcastable funding tx, the channel transitions to
AWAITING_UNILATERAL and CLN tries to broadcast a commitment tx that
spends the (non-existent) funding output. That commit tx can never
confirm either, so the channel record sits stuck in
AWAITING_UNILATERAL indefinitely.

Same setup as the first test (mock_rpc on sendrawtransaction +
dev-max-funding-unconfirmed-blocks=10); diverges by stopping l2 and
calling close with unilateraltimeout=1 to force AWAITING_UNILATERAL,
then asserts the channel is no longer in that state after THRESHOLD+5
blocks.

Kept as a separate commit so it can be split off if maintainers prefer
to address the two stuck states independently.