Helm Chart: Add support for tolerations

[oWretch]

Proposed changes

Add support for defining tolerations in the Helm chart.

Problem: We run a separate nodepool for system services which has taints applied, and we therefore need the relevant tolerations to be applied to the pod.

Solution: Add support for tolerations to be supplied if required. If not provided, there is no change the the deployment

Testing: Validate deployment both with and without tolerations.

Closes #1196

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[kate-osborn]

Thanks for the PR @oWretch!

Typically, we require that every PR is associated with an issue. Issues help us prioritize and refine features before working on them. Since this PR is straightforward and has a good description (very appreciated!) I went ahead and filed an issue for it: #1196. Feel free to add any missing context.