[exporter/elasticsearch] Fix retry backoff overflow handling edge case (open-telemetry#46178)

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#### Description

Guard exponential retry backoff against duration overflow so delay
growth remains bounded and correctly caps at max_interval while
preserving jitter.

Co-authored-by: Cursor <cursoragent@cursor.com>

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---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: carsonip

.chloggen/elasticsearch-retry-backoff-overflow.yaml

@@ -0,0 +1,9 @@
+change_type: bug_fix
+component: exporter/elasticsearch
+note: Fix retry exponential backoff overflow handling edge case
+issues: [46178]
+subtext: |
+  The retry delay growth now guards against duration overflow while preserving
+  exponential backoff with jitter, so retries cap correctly at the configured
+  max interval even for large attempt counts.
+change_logs: [user]

exporter/elasticsearchexporter/esclient.go

@@ -260,13 +260,17 @@ func addrsToURLs(addrs []string) ([]*url.URL, error) {
 	return urls, nil
 }
 
+// createElasticsearchBackoffFunc creates an exponential backoff with equal jitter.
 func createElasticsearchBackoffFunc(config *RetrySettings) func(int) time.Duration {
 	if !config.Enabled {
 		return nil
 	}
 
 	return func(attempts int) time.Duration {
-		next := min(config.MaxInterval, config.InitialInterval*(1<<(attempts-1)))
+		next := config.InitialInterval << (attempts - 1) // config.InitialInterval * 2 ^ (attempts - 1)
+		if next <= 0 || next > config.MaxInterval {      // guard against overflow
+			next = config.MaxInterval
+		}
 		nextWithJitter := next/2 + time.Duration(rand.Float64()*float64(next/2))
 		return nextWithJitter
 	}