Chart bools rendered into environment values need to be stringified

[kdubb]

When setting an enabled boolean (grpc.tls.enabled) that is forwarded to an environment variable Helm fails to render the chart. The chart requires a boolean for these but the spec for environment variables requires all the keys/values to be strings.

There may be others, but the variables I had issues with are:

• grpc.tls.enabled
• http.tls.enabled