Missing space when concat the msg lines, sentence too long

[plaformsre]

Current:
This node image upgrade operation will run across every node pool in the clusterand might take a while, do you wish to continue

Proposed:
This node image upgrade operation will run across every node pool in the cluster and might take a while. Do you wish to continue

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

About Extension Publish

There is a pipeline to automatically build, upload and publish extension wheels.
Once your PR is merged into master branch, a new PR will be created to update src/index.json automatically.
The precondition is to put your code inside this repo and upgrade the version in the PR but do not modify src/index.json.

[ghost]

Thank you for your contribution mapdegree! We will review the pull request and get back to you soon.

[yonzhan]

aks