fix(alloy): fix log level parser

- remove parser for JSON and logfmt, and add regex expression to extract the level of log

config/services/systemd/common/alloy/config.alloy.j2

@@ -203,17 +203,11 @@ loki.relabel "caddy_relabel" {
 loki.process "journal_parser" {
         forward_to = [loki.write.loki.receiver]
         // Severity parsing
-        // If content of log includes "level" information, change the level
+        stage.regex {
-        stage.json {
+            // Regex to extract the log level from the content.
-            expressions = {
+            expression = "(?i)(?:level[\"\\s:=]+|\\[|\\s|^)(?P<content_level>info|warn|warning|error|debug|fatal|critical|trace)(?:[\"\\]\\s]|$)"
-                "content_level" = "level",
-            }
-        }
-        stage.logfmt {
-            mapping = {
-                "content_level" = "level",
-            }
         }
+        
         stage.labels {
             values = {
                 "level" = "content_level",