Move resource download to pytest code

[marceloneppel]

Move the download process of the Patroni resource (and any other resource) to the pytest code and use the Charmhub API to get it.

[taurus-forever]

@marceloneppel AFAIK all bits are coming from snap nowadays. Is it still topical?
CC: @dragomirp do you recall bits outside of our control?

[dragomirp]

@marceloneppel AFAIK all bits are coming from snap nowadays. Is it still topical? CC: @dragomirp do you recall bits outside of our control?

Patroni used to be a resource, but it's now in the snap. I don't think this is still topical.

[dragomirp]

Closing since Patroni is now part of the charmed-postgresql snap