x-pack/filebeat/input/cel: make now evaluate to a time in UTC (#37159) (

#37163)

now() and the mito now global both evaluate as times in UTC. The
per-period now global of the input should as well.

(cherry picked from commit c438382)

Co-authored-by: Dan Kortschak <90160302+efd6@users.noreply.github.com>

CHANGELOG.next.asciidoc

@@ -72,6 +72,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Fix Filebeat Cisco module with missing escape character {issue}36325[36325] {pull}36326[36326]
 - Do not error when Okta API returns no data. {pull}37092[37092]
 - Fix request body close behaviour in HTTP_Endpoint when handling GZIP compressed content. {pull}37091[37091]
+- Make CEL input now global evaluate to a time in UTC. {pull}37159[37159]
 
 *Heartbeat*
 

x-pack/filebeat/input/cel/input.go

@@ -228,7 +228,7 @@ func (i input) run(env v2.Context, src *source, cursor map[string]interface{}, p
 			// Process a set of event requests.
 			log.Debugw("request state", logp.Namespace("cel"), "state", redactor{state: state, cfg: cfg.Redact})
 			metrics.executions.Add(1)
-			start := i.now()
+			start := i.now().In(time.UTC)
 			state, err = evalWith(ctx, prg, state, start)
 			log.Debugw("response state", logp.Namespace("cel"), "state", redactor{state: state, cfg: cfg.Redact})
 			if err != nil {