fix: null processor helm value being removed by newer helm versions when merging

[tim-mwangi]

Description

In newer helm versions if the helm value being merged from a custom values.yaml has a null value, it's removed. So for the hypertrace_metrics_resource_attrs_to_attrs we will modify it to hypertrace_metrics_resource_attrs_to_attrs: {}

Testing

Verified that the collector comes up locally

Checklist:

• [ ✅ ] My changes generate no new warnings
• [ ✅ ] Any dependent changes have been merged and published in downstream modules