Support $rate_interval when parsing Query during dashboards analysis

[wilfriedroset]

Grafana support several Global variables but also allow users to define an interval templated variable. When using mimirtool on such case we might have the following error:

"query=histogram_quantile(0.70, sum by (le) (rate(rpc_server_duration_milliseconds_bucket{rpc_method=~\"$gRPC_method\", job=\"$job\"}[$rate_interval]))): 1:124: parse error: missing unit character in duration",

This commit add support for more user define variables matching the global ones.

See: https://grafana.com/docs/grafana/latest/dashboards/variables/add-template-variables/#global-variables

We have the following global variables that are out of the scope of dashboards analysis:

• $__dashboard
• $__from and $__to
• $__name
• $__org
• $__user
• $timeFilter or $__timeFilter
• $__timezone

However those are interesting:

• $__interval --> can be overridden by $interval
• $__interval_ms --> can be overridden by $interval
• $__range --> not addressed by this PR, should we?
• $__rate_interval --> can be overridden by $rate_interval
• $__rate_interval_ms --> can be overridden by $rate_interval

What this PR does

Which issue(s) this PR fixes or relates to

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[colega]

We have an internal tool that does a similar job, and instead of a list of string replaces it just does:

var variableRangeQueryRangeRegex = regexp.MustCompile(`\[\$?\w+?]`)
var variableSubqueryRangeRegex = regexp.MustCompile(`\[\$?\w+:\$?\w+?]`)

func removeVariablesFromRanges(query string) string {
	query = variableRangeQueryRangeRegex.ReplaceAllLiteralString(query, `[5m]`)
	query = variableSubqueryRangeRegex.ReplaceAllLiteralString(query, `[5m:1m]`)
	return query
}

WDYT about applying it here?

[colega]

Nice! Would you mind adding a CHANGELOG entry? 🙏 Then we're good to go.

[colega]

Thank you!