Automatically round container instance memory to the first decimal place

[ninjarobot]

The container instances in container groups must have memory defined in increments of 0.1 GB, otherwise it will give an error of:The memory requirement should be in increments of 0.1 GB

The changes in this PR are as follows:

• Container Groups: Automatically round container instance memory to the first decimal place.

I have read the contributing guidelines and have completed the following:

• [x] Tested my code end-to-end against a live Azure subscription.
• [ ] Updated the documentation in the docs folder for the affected changes.
• [x] Written unit tests against the modified code that I have made.
• [x] Updated the release notes with a new entry for this PR.
• [x] Checked the coding standards outlined in the contributions guide and ensured my code adheres to them.

If I haven't completed any of the tasks above, I include the reasons why here:

Validation change only, so no doc update.