adding networkpolicy for thanos components

[harsh-ps-2003]

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

Fixes #314
Adding network policies for all Thanos components.

[harsh-ps-2003]

@metalmatze can you review the PR please. If it looks good I will add the changelog.

[metalmatze]

Thanks!
From looking at the code changes and now having compiled and run this, the change seems good overall. 👍

Some CI failures need to be fixed. Run jsonnetfmt -i $file on your changed files.

[harsh-ps-2003]

Thanks for the review! I had some syntax errors that I fixed now! @metalmatze