The normalization of the `instance` tag on the http_check is done incorrectly

[tsullivan22]

The normalization described here is incorrect for tags

https://github.com/DataDog/integrations-core/blob/master/http_check/datadog_checks/http_check/data/conf.yaml.example#L51

The above states that - will be converted to underscores despite the documentation saying that minuses are valid for tags

docs

May contain alphanumerics, underscores, minuses, colons, periods, and slashes. Other characters are converted to underscores.

And if we look to other instance name to tag conversions, minuses are left as is. Postgres for instance leaves minuses as valid.
https://github.com/DataDog/integrations-core/blob/master/postgres/datadog_checks/postgres/data/conf.yaml.example#L75

From an enduser perspective there is no consistency and this leads to unexpected behavior.