pytest: Remove all trace of python's "flaky" module.

Over time, it has cost us more developer cycles than it has gained.
It has hidden intermittant bugs, and allowed cruft to accumulate:
when we eventually tried to figure out what was going wrong, the
actual change which caused it was now stale and forgotten.

This was a particular bane during the connectd rewrite, and I
worked through some issues which had occurred before, but were not
more likely.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/test_connection.py

@@ -1,6 +1,5 @@
 from fixtures import *  # noqa: F401,F403
 from fixtures import TEST_NETWORK
-from flaky import flaky  # noqa: F401
 from ephemeral_port_reserve import reserve  # type: ignore
 from pyln.client import RpcError, Millisatoshi
 import pyln.proto.wire as wire
@@ -658,7 +657,6 @@ def test_reconnect_gossiping(node_factory):
     l2.daemon.wait_for_log('processing now old peer gone')
 
 
-@flaky
 @pytest.mark.developer("needs dev-disconnect")
 @pytest.mark.openchannel('v1')
 @pytest.mark.openchannel('v2')
@@ -853,7 +851,6 @@ def test_reconnect_receiver_fulfill(node_factory):
     assert only_one(l2.rpc.listinvoices('testpayment2')['invoices'])['status'] == 'paid'
 
 
-@flaky
 @pytest.mark.developer
 @pytest.mark.openchannel('v1')
 @pytest.mark.openchannel('v2')
@@ -886,7 +883,6 @@ def test_shutdown_reconnect(node_factory):
     assert l1.bitcoin.rpc.getmempoolinfo()['size'] == 1
 
 
-@flaky
 @pytest.mark.developer
 def test_reconnect_remote_sends_no_sigs(node_factory):
     """We re-announce, even when remote node doesn't send its announcement_signatures on reconnect.