Automatic merge from submit-queue (batch tested with PRs 49019, 48919, 49040, 49018, 48874)

Set default snap channel on charms to 1.7 stable

**What this PR does / why we need it**: This PR sets the default snap channel on charms to 1.7/stable. 
This addresses problems where the the user might want to deploy the charm and get the same kubernetes version found on the bundles.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes https://github.com/juju-solutions/bundle-canonical-kubernetes/issues/305

**Special notes for your reviewer**:

**Release note**:

```Set default snap channel on charms to 1.7/stable
```