As described in #5105, it's not currently possible to set the proxy log
level to `off`. The proxy injector's template does not quote the log
level value, and so the `off` value is handled as `false`. Thanks, YAML.
This change updates the proxy template to use helm's `quote` function
throughout, replacing manually quoted values and fixing the quoting for
the log level value.
We also remove the default logFormat value, as the default is specified
in values.yaml.
f0820bdfbf