instance: accept ready as valid running state

[jasisk]

Did a little archeology and it seems like this was just a tiny tiny oversight when the helper functions were introduced.

Compiled and tested against the testcase in #391:

incus_instance.testcase: Creating...
incus_instance.testcase: Creation complete after 8s [name=testcase]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Calling out there's one more instance where the helper isn't used but I didn't update it since it bails out early. Guess it's still possible this could bork if it goes to "ready" quickly enough so I'm happy to if you'd rather!

Fixes #391

[stgraber]

@jasisk can you edit the commit message to include the Signed-off-by line?

[jasisk]

can you edit the commit message to include the Signed-off-by line?

@stgraber oops, sorry. Forgot to sign and sign-off. Done.

[maveonair]

@jasisk could you please follow the commit message guideline from CONTRIBUTION.md?

[jasisk]

could you please follow the commit message guideline from CONTRIBUTION.md?

@maveonair I added the resource type prefix. Is the rest of the message good?
What do you think about the other usage of the hardcoded "Running" mentioned in the PR body?

[stgraber]

@jasisk a quick rebase would let the tests all clear now that the other PR has landed

[stgraber]

I'll let @maveonair check for the commit message and otherwise we should be good to go, thanks!

[maveonair]

@jasisk Thanks a lot!