Tests: fix missing PermitTTY in RemoteSshdConfig Reset

[mus65]

this fixes a test failure in Common_CreateMoreChannelsThanMaxSessions when running the tests multiple times against the same SSH server instance. The failure is specifically triggered by SshTests_TTYDisabled.SetUp() calling PermitTTY(false), but Reset() not setting it back to true.

this was noticed in #1704 (comment) .

To repro, you have to modify InfrastructureFixture.InitializeAsync() to always use the local container instead of setting one up with Testcontainers.

Then run the following. This uses podman, but should in theory also work with docker.

#!/bin/bash -e
podman build -t renci-ssh-tests-server-image -f test/Renci.SshNet.IntegrationTests/Dockerfile test/Renci.SshNet.IntegrationTests/
dotnet build -f net9.0 test/Renci.SshNet.IntegrationTests/Renci.SshNet.IntegrationTests.csproj

podman container rm -f -t 0 sshserver || true
podman run --rm -h renci-ssh-tests-server -d -p 2222:22 --name sshserver renci-ssh-tests-server-image

filter="FullyQualifiedName~ConnectivityTests.Common_CreateMoreChannelsThanMaxSessions|FullyQualifiedName~SshTests_TTYDisabled.Ssh_CreateShellNoTerminal"

dotnet test -f net9.0 --tl:off -v normal --no-build test/Renci.SshNet.IntegrationTests/Renci.SshNet.IntegrationTests.csproj
dotnet test -f net9.0 --tl:off -v normal --no-build test/Renci.SshNet.IntegrationTests/Renci.SshNet.IntegrationTests.csproj

[mus65]

Merged this into #1704 because it may fix another test failure there.