[libbeat] Cache processor docs and memory fixes.

CHANGELOG.next.asciidoc

@@ -72,6 +72,7 @@ fields added to events containing the Beats version. {pull}37553[37553]
 - Lower logging level to debug when attempting to configure beats with unknown fields from autodiscovered events/environments {pull}[37816][37816]
 - Set timeout of 1 minute for FQDN requests {pull}37756[37756]
 - Fix the paths in the .cmd script added to the path by the Windows MSI to point to the new C:\Program Files installation location. https://github.com/elastic/elastic-stack-installers/pull/238
+- Change cache processor option `write_interval` to `write_period` to match documentation. {pull}38561[38561]
 
 *Auditbeat*
 

libbeat/processors/cache/config.go

@@ -105,7 +105,7 @@ type memConfig struct {
 
 type fileConfig struct {
 	ID            string        `config:"id" validate:"required"`
-	WriteOutEvery time.Duration `config:"write_interval"`
+	WriteOutEvery time.Duration `config:"write_period"`
 }
 
 func (cfg *storeConfig) Validate() error {

libbeat/processors/cache/config_test.go

@@ -48,7 +48,7 @@ put:
 backend:
   file:
     id: aidmaster
-    write_interval: 15m
+    write_period: 15m
 put:
   ttl: 168h
   key_field: crowdstrike.aid