Fix code scanning alert no. 494: Incomplete string escaping or encodi…

…ng (elastic#204528)

Fixes
[https://github.com/elastic/kibana/security/code-scanning/494](https://github.com/elastic/kibana/security/code-scanning/494)
Fixes elastic#1311

Escape first backslash occurrences and all single quotes in the `filter`
string.

x-pack/solutions/observability/plugins/observability/public/components/rule_condition_chart/helpers.ts

@@ -18,7 +18,7 @@ export const getLensOperationFromRuleMetric = (metric: GenericMetric): LensOpera
   const { aggType, field, filter = '' } = metric;
   let operation: string = aggType;
   const operationArgs: string[] = [];
-  const escapedFilter = filter.replace(/'/g, "\\'");
+  const escapedFilter = filter.replace(/\\/g, '\\\\').replace(/'/g, "\\'");
 
   if (aggType === Aggregators.RATE) {
     return {