Fix: Remove regex pattern length restriction (#2087)

In this PR I removed the regex pattern length restriction because from
multi value variables this length can be easly reached, also if the
regex is going to be too long it will be caught in the timeout.

Fixes #2086

pkg/zabbix/utils.go

@@ -155,11 +155,6 @@ func parseFilter(filter string) (*regexp2.Regexp, error) {
 		return nil, backend.DownstreamErrorf("error parsing regexp: potentially dangerous regex pattern detected")
 	}
 
-	// Security: Limit regex pattern length
-	if len(regexPattern) > 1000 {
-		return nil, backend.DownstreamErrorf("error parsing regexp: pattern too long (max 1000 characters)")
-	}
-
 	pattern := ""
 	if matches[2] != "" {
 		if flagRE.MatchString(matches[2]) {