tl;dr We were not counting cells flying from the client to the service, but we
were counting cells flying from the service to the client.

When a rendezvous cell arrives from the client to the RP, the RP forwards it to
the service.

For this to happen, the cell first passes through command_process_relay_cell()
which normally does the statistics counting. However because the `rend_circ`
circuit was not flagged with `circuit_carries_hs_traffic_stats` in
rend_mid_rendezvous(), the cell is not counted there.

Then the cell goes to circuit_receive_relay_cell() which has a special code
block based on `rend_splice` specifically for rendezvous cells, and the cell
gets directly passed to `rend_circ` via a direct call to
circuit_receive_relay_cell(). The cell never passes through
command_process_relay_cell() ever again and hence is never counted by our
rephist module.

The fix here is to flag the `rend_circ` circuit with
`circuit_carries_hs_traffic_stats` so that the cell is counted as soon as it
hits command_process_relay_cell().

Furthermore we avoid double-counting cells since the special code block of
circuit_receive_relay_cell() makes us count rendezvous cells only as they enter
the RP and not as they exit it.

Fixes #40117.

Fixes #40105.

Turns out that the HS DoS defenses parameters were overwritten by the
consensus parameters everytime a new consensus would arrive.

This means that a service operator can still enable the defenses but as soon
as the intro point relay would get a new consensus, they would be overwritten.
And at this commit, the network is entirely disabling DoS defenses.

Fix this by introducing an "explicit" flag that indicate if the
ESTABLISH_INTRO cell DoS extension set those parameters or not. If set, avoid
using the consenus at once.

We are not bumping the protover HSIntro value for this because 0.4.2.x series
is EOL in 1 month and thus 0.4.3.x would be the only series with this bug. We
are confident that a backport and then upgrade path to the latest 0.4.4.x
stable coming up soon is enough to mitigate this problem in the coming months.

It avoids the upgrade path on the service side by keeping the requirement for
protover HSIntro=5.

Fixes #40109

Signed-off-by: David Goulet <dgoulet@torproject.org>

First, we introduce a flag to teach src/test/test to split its work
into chunks.  Then we replace our invocation of src/test/test in our
"make check" target with a set of 8 scripts that invoke the first
8th of the tests, the second 8th, and so on.

This change makes our "make -kj4 check" target in our hardened
gitlab build more than twice as fast, since src/test/test was taking
the longest to finish.

Closes 40098.

Without this fix, running this test on its own would fail.

Fixes bug 40099. Bugfix on ade50058 in 0.2.8.1-alpha.

"ours" merge to avoid MR 122 -- we already merged MR 123.

For clients, there is no minimum value; in both cases, we warn if
the value seems too low.

Closes ticket 24308.