[DPE-5098] Tests for mongos / mongodb integration

[Gu1nness]

Description

This PR adds the test in mongodb-k8s to check for the validity and stability of the integration between the newly developed mongos-k8s charm which handles the connection with outside applications, and the sharded deployment (on mongodb-k8s side).

What it does:

• Integrate tests for mongos / mongodb integration in k8s

How it has been checked:

• Tests are green with manual deployment (waiting for PR 20 to be merged to enable it fully)

Instructions for manual check:

• Build local charms

juju add-model integ-test

cd <mongodb-k8s-operator>
git checkout DPE-5098-mongo-db-k-8-s-tests-add-config-server-mongos-integration-tests
tox -e build-production
juju deploy ./*charm --config role="shard" shard-one -n1  --resource mongodb-image=ghcr.io/canonical/charmed-mongodb:6.0.6-22.04_edge@sha256:b4b3edb805b20de471da57802643bfadbf979f112d738bc540ab148d145ddcfe
juju deploy ./*charm --config role="config-server" config-server-one -n1  --resource mongodb-image=ghcr.io/canonical/charmed-mongodb:6.0.6-22.04_edge@sha256:b4b3edb805b20de471da57802643bfadbf979f112d738bc540ab148d145ddcfe

cd <mongos-k8s-operator
git checkout DPE-5040-mongos-config-svr
tox -e build-production
juju deploy ./*charm --resource mongodb-image=ghcr.io/canonical/charmed-mongodb:6.0.6-22.04_edge@sha256:b4b3edb805b20de471da57802643bfadbf979f112d738bc540ab148d145ddcfe

cd <mongodb-k8s-operator>
tox -e integration -- tests/integration/sharding_tests/test_mongos.py  --model=integ-test

Miscellaneous

• Small fix in tls tests, a call was never awaited