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

.changeset/soft-kids-watch.md

@@ -0,0 +1,5 @@
+---
+'grafana-zabbix': patch
+---
+
+Fix: Remove regex pattern length restriction

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]) {

pkg/zabbix/utils_test.go

@@ -2,7 +2,6 @@ package zabbix
 
 import (
 	"reflect"
-	"strings"
 	"testing"
 
 	"github.com/dlclark/regexp2"
@@ -124,13 +123,6 @@ func TestParseFilter(t *testing.T) {
 			expectNoError: false,
 			expectedError: "error parsing regexp: potentially dangerous regex pattern detected",
 		},
-		{
-			name:          "Pattern too long",
-			filter:        "/" + strings.Repeat("a", 1001) + "/",
-			want:          nil,
-			expectNoError: false,
-			expectedError: "error parsing regexp: pattern too long (max 1000 characters)",
-		},
 		{
 			name:          "Safe complex regex",
 			filter:        "/^[a-zA-Z0-9_-]+\\.[a-zA-Z]{2,}$/",