[Redis] Add support for sanitisation from environment variable

[danwiltshire]

The Redis instrumentation now supports sanitisation. I'd like to use this via auto instrumentation so an environment variable must be configured.

When running auto instrumentation with environment variable OTEL_PYTHON_INSTRUMENTATION_SANITIZE_REDIS set to true, I expect sanitisation to be enabled.

A more interesting change could be to support kwargs being passed to instrumentations from environment variables.